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Fio.  1.  —  Model  of  the  Human  Brain  [Auzouxj 


ELEMENTS  OF 
HUMAN  PSYCHOLOGY 


BY 
HOWARD  C.  WARREN 

STUART  PROFESSOR  OF  P8TCHOU)GT,  PRINCETON  UNIVEBSITT 
AUTHOR  OP  HUMAN  PSTCHOLOQT 


HOUGHTON  MIFFLIN  COMPANY 

BOSTON      NEW  YORK      CHICAGO      SAN  FRANCISCO 


COPYRIGHT,  1922 

BY  HOWARD  C  WARREN 
ALL  SIGHTS  RESERVES) 


CAMBRIDGE  •  MASSACHUSETTS 
PRINTED  IN  THE  U.S.A. 


CONTENTS 


CHAPTER  PAGK 

I.   SUKVEY  OF  THE  FlELD 1 

.  19 

.  39 

.  57 

.  85 
105; 


II.  Structure  of  the  Nervous  System 

III.  Operation  of  the  Nervous  System 

rV.  The  Senses:  Sight 

V.  The  Senses:  Hearing  and  Other  Senses 

Hearing,  85;  Smell,  98;  Taste,  103;  Cutaneous  Senses, 
Organic  Senses,  109;  Fain,  113;  Muscle  Sense,  114;  Static 
Sense,  117 

VI.  Conscious  Life 121 

VII.  Perception 143 

VUI.  Memory  and  Imagination 178 

IX.  Feeling  and  Emotion 203 

Feeling,  203;  Emotion,  209;  Sentiment,  218 

X.  Instinct 224 

Reflex  Behavior,  229;  Instinctive  Behavior,  234 

XI.  Intelligence 247 

Conditioned  Reflexes,  248;  Intelligent  Behavior,  250 

Xn.  Volition 271 

Conation,  272;  Volition,  274;  Ideals,  281 

Xm.  Language  and  Thought 284 

XIV.  Mental  Succession         306 

XV.  Human  Character 331 

Attitude,  332;  Character,  345 

XVI.  Personality  and  Control 360 

Review  Questions 383 

Suggestions  in  Using  the  Book 391 

Glossary  and  Index 395 


ILLUSTRATIONS 

nGURE                                                                                                                  CHAPTER  PAGE 

1.  Model  of  the  Human  Brain Frontispiece 

2.  Seeing  and  Acting I  4 

S.  Different  Kinds  of  Cells II  20 

4.  The  Neuron  and  its  Parts "  21 

5.  Various  Types  of  Neurons "  22 

6.  Various  Types  of  SjTiapses "  23 

7.  Brain  and  Cord  in  Position "  24 

8.  Central  Portion  of  Nervous  System "  25 

9.  Cross-Section  of  Cord "  27 

10.  Base  of  Brain facmg  "  28 

11.  Middle  Cross-Section  of  Brain        .      .      .      .     "  "  29 

12.  Cortex  from  Above "  "  30 

13.  Cortex  from  Left  Side "  "  31 

14.  Centers  in  the  Cortex "  32 

15.  Autonomic  Nervous  System "  35 

16.  Nervous  Arc  in  Spinal  Reflex HI  41 

17.  Collection  of  Nerve  Impulses "  47 

18.  Distribution  of  a  Nerve  Impulse "  47 

19.  Muscle  with  Nerve  Endings "  50 

20.  Diagram  of  Muscular  Contraction "  50 

21.  Cross-Section  of  Eye IV  59 

22.  Layers  of  the  Retina "  61 

23.  Map  of  Blind  Spot "  62 

24.  How  to  Find  the  Blind  Spot "  63 

25.  Eyeball  and  Eye  Muscles "  64 

26.  Focusing  Objects  on  the  Retina "  65 

27.  Course  of  the  Optic  Nerve "  66 

28.  Long  and  Short  Light  Waves "  68 

29.  Refraction  of  Light "  68 

30.  Color  Mixer "  69 

31.  Color  Spindle  and  Color  Belt "  71 

32.  Series  of  Color-Shades  and  Tints "  72 

83.  Perimeter "  74 

S4.  Contrast  Color "  78 


vi        ELEMENTS  OF  HUMAN  PSYCHOLOGY 

FIGURE                                                                                                                      CHAPTER  PAGE 

35.  Color  Zones  of  the  Retina IV  81 

36.  Cross-Section  of  Ear V  85 

37.  Labyrinth  of  the  Ear "  87 

38.  Section  through  Cochlea "  88 

39.  Organ  of  Corti "  89 

40.  Musical  Intervals "  93 

41.  How  Overtones  are  Made "  94 

42.  Nasal  Cavity  and  Olfactory  Region "  98 

43.  Olfactory  Cells "  99 

44.  Odor  Prism "  101 

45.  Olfactometer "  102 

46.  Tongue,  Showing  Papillae facing  "  103 

47.  Taste  Bulbs  and  Taste  Cells "  103 

48.  Pressure  and  Temperature  Spots "  107 

49.  Cutaneous  Receptors "  108 

50.  Semicircular  Canals  and  Sacs "  117 

51.  Jastrow  Cylinders VI  137 

52.  Filled-in  Perception VII  144 

53.  Illusion  of  the  Crosses "  145 

54.  Curve  of  Weber's  Law "  148 

55.  Space  Perception  in  Touch "  150 

56.  Visual  Space  Perception "  151 

57.  Convergence  of  the  Eyes "  156 

58.  Stereoscope "  158 

59.  Who  is  This? "  164 

60.  Double  Interpretation "  169 

61.  The  Illusory  Cubes "  169 

62.  The  Reversible  Cube "  169 

63.  The  Reversible  Staircase "  169 

64.  Muller-Lyer  Illusion "  170 

65.  Bering  Illusion "  170 

66.  Zollner  Illusion "  171 

67.  Poggendorff  Illusion "  172 

68.  Vineland  Form-Board "  175 

69.  Curve  of  Forgetting VIII  190 

70.  Intensity  of  Feeling IX  208 

71.  Simple  Reflex X  231 

72.  Distributed  Reflex "  232 

73.  Mazes  for  Investigating  Habit  Formation          ...  XI  252 

74.  Changes  of  Path  in  Habit  Formation "  254 

75.  Curve  of  Learning ,  "  259 


ILLUSTRATIONS  vii 

FIGURE                                                                                                                CHAPTER  PAGE 

76.  Reading  Mirror  Script XIII  290 

77.  Language  Centers  in  the  Cortex "  293 

78.  Mental  Levels "  303 

79.  Hipp  Chronoscope XIV  309 

80.  Handwriting  with  Different  Muscles XVI  368 


PREFACE 

This  book  was  written  to  meet  numerous  requests  for  an 
introductory  text-book  of  psychology  based  on  the  functions 
of  the  nervous  system.  The  standpoint  is  the  same  as  that  of 
Human  Psychology,  which  recognizes  both  the  introspective 
and  behavioristic  methods.  Material  has  been  freely  drawn 
from  the  earlier  work,  but  the  arrangement  of  topics  is  differ- 
ent and  the  treatment  has  been  simphfied.  Most  of  the  theo- 
retical discussions  are  omitted  and  the  practical  applications 
of  psychology  are  emphasized. 

Where  the  book  is  used  as  a  class  text,  the  instructor  is  re- 
ferred to  the  Suggestions  on  page  391. 

Besides  the  assistance  acknowledged  in  Human  Psychology, 
thanks  are  due  to  A.  P.  Weiss,  H.  S.  Langfeld,  E.  M.  Weyer, 
C  M.  Cantrall  and  his  students,  and  Alvin  Bruch  for  many 
valuable  criticisms  and  to  numerous  others  for  helpful  sugges- 
tions. I  am  especially  indebted  to  my  colleagues,  Henry  C. 
McComas  and  Carl  C.  Brigham,  for  reading  the  manuscript 
critically,  and  to  my  oflGice  assistants  for  painstaking  aid  in 
preparing  the  manuscript  and  proof. 

Acknowledgments  are  due  to  the  following  authors  and 
publishers  for  permission  to  make  use  of  illustrations  from 
the  works  mentioned:  C.  J.  Herrick,  Introduction  to  Neurology 
(W.  B.  Saunders  Co.) ;  Knight  Dunlap,  Outline  of  Psychohi- 
ology  (Johns  Hopkins  Press);  E.  A.  Schaefer,  Text-hook  of 
Physiology  (Macmillan  Co.);  E.  L.  Thorndike,  Elements  of 
Psychology  (A.  G.  Seller) ;  J.  D.  Lickley,  The  Nervous  System 
(Longmans,  Green  &  Co.) ;  Joseph  Jastrow,  Fact  and  Fable  in 
Psychology  (Houghton  Mifflin  Co.);  C.  H.  Judd,  Laboratory 
Equipment  for  Psychological  Experiments  (C.  H.  Judd) ;  E.  J. 


X  PREFACE 

Swift,  article  in  Psychological  Bulletin  (Psychological  Review 
Co.);  R.  M.  Yerkes,  in  Harvard  Psychological  Studies  (Har- 
vard Psychological  Laboratory);  Helen  B.  Hubbert,  in 
Journal  of  Animal  Behavior  (Henry  Holt  &  Co.) ;  The  Farm 
Journal  (W.  Atkinson  Co.). 

Howard  C.  Warren 

Pbinceton,  New  Jebsft 
May,  1922 


ELEMENTS  OF 
HUMAN  PSYCHOLOGY 

CHAPTER  I 
SURVEY  OF  THE  FIELD 

Meaning  of  the  Term  *  Psychology/  —  The  word  psychology 
is  often  used  in  conversation  and  in  newspapers  or  popular 
magazines  without  a  very  clear  idea  of  its  meaning.  In  most 
cases  the  speaker  or  writer  is  referring  to  human  nature;  he 
thinks  the  mysterious  term  psychology  sounds  more  dignified 
and  imposing,  just  as  stilted  writers  speak  of  the  *  celestial 
luminary  *  when  they  really  mean  the  sun.  Psychology  does 
not  mean  human  nature;  but  it  does  mean  something  very 
nearly  equivalent  to  the  study  of  human  nature.  Human 
psychology  is  the  systematic  study  of  man's  daily  experi- 
ences. It  is  not  merely  a  description  of  our  doings,  feelings, 
^pMHroughts,  but  an  attempt  to  discover  why  we  act  and  feel 
and  think  as  we  do. 

Thinking  and  doing  things  is  not  studying  psychology,  any 
more  than  tossing  a  ball  is  studying  physics,  or  mixing  a  Seid- 
litz  powder  is  studying  chemistry.  In  either  case  the  action 
may  be  the  starting-point  for  systematic  study;  but  the  study 
itself  involves  a  great  number  of  accurate  observations,  and 
these  observations  must  be  put  together  in  an  orderly  way 
before  we  can  discover  their  causes  and  relations.  In  other 
words,  when  we  make  a  serious  business  of  studying  any  class 
of  events  in  nature  we  (1)  collect  a  large  body  of  facts,  (2) 
classify  them,  and  (3)  try  to  explain  how  they  come  to  pass. 
This  is  what  is  meant  by  scientific  investigation.  The  results 
obtained  in  this  way  make  up  the  science  —  physics,  chemis- 
try, or  psychology,  as  the  case  may  be. 


ft  THE  FIELD  OF  PSYCHOLOGY  [ch.  i 

Psychology  is  concerned  with  the  scientific  investigation  of 
feelings,  thoughts,  actions,  and  other  events  of  life.  Many  of 
these  occurrences  are  by  no  means  confined  to  man.  Dogs 
see,  hear,  and  act.  The  ant  is  found  to  possess  a  keen  sense 
of  smell.  Even  the  amoeba,  one  of  the  very  lowest  known 
species  of  animal,  reacts  in  quite  definite  ways  to  certain  ob- 
jects outside  of  itself  which  affect  it.  The  field  of  psychology 
embraces  all  these  occurrences.  It  includes  the  study  not 
only  of  human  beings,  but  of  all  species  of  animals. 

Psychology  is  not  concerned  with  life  in  general,  but  only 
with  certain  definite  sorts  of  events  in  life.  It  is  not  the 
study  of  bodily  growth,  nor  of  digestion  or  the  other  processes 
which  maintain  the  body.  The  events  which  we  study  in 
psychology  are  of  a  different  sort  from  these.  They  have  to 
do  with  the  interaction  between  the  living  creature  and  the  world 
in  which  he  lives. 

Every  living  creature  is  continually  being  acted  upon  by 
the  surrounding  world  (his  '  environment '),  and  in  conse- 
quence he  reacts  upon  his  surroundings.  First  the  environ- 
ment affects  the  creature;  then  the  creature  produces  some 
change  in  the  environment.  Some  of  these  changes  are  very 
obvious ;  when  you  open  a  door,  or  when  your  dog  paws  a  hole 
in  the  ground,  the  position  of  things  in  the  outer  world  is 
altered.  In  other  cases  the  change  in  the  environment  is  not 
so  evident.  But  even  when  you  merely  turn  your  head  you 
see  things  differently;  your  visual  environment  is  different. 
There  is  always  some  change  in  a  creature's  environment 
when  he  reacts. 

Our  feelings,  thoughts,  and  volitions  arise  in  connection 

with  this  interplay  between  our  bodily  organization  and  our 

environment.     These  n^rj^nal  experiences,  and  all  the  other 

^events  that  occur  while  the  reaction  is  proceeding,  are  what 

we  haYfiJ:Q-st"diY  h  r''y''^"lt^g'  ' 

'  Some  chemical  and  physical  reactions  between  the  body  and  its  sur- 
roundings, such  as  absorbing  food-stuff,  the  action  of  oxygen  on  the  lungs. 


CH.  i]  MEANING  OF  THE  TERM  8 

This  special  kind  of  interplay  between  the  creature  and  his 
surroundings  is  called  mental  life.  It  takes  place  in  a  very 
definite  way.  (1)  Men  and  animals  have  a  number  of  special 
receiving  organs,  called  receptors,  such  as  the  eye  and  ear, 
which  gather  in  the  impressions  from  outside.  (2)  There  are 
motor  organs,  called  muscles,  distributed  throughout  the 
body,  which  enable  the  creature  to  move  in  various  ways. 
(3)  The  receptor  organs  are  connected  with  the  motor  organs 
by  means  of  a  vast  network  of  permanent  pathways  called 
nerves,  along  which  certain  impulses  travel. 

The  nerves  do  not  connect  the  receptors  directly  with  the 
muscles;  they  extend  from  the  receptors  up  to  the  brain  and 
from  the  brain  down  to  the  motor  organs.  The  brain  is  the 
connecting  link.^  It  consists  of  a  mass  of  nerve  cells  and 
fibers  which  join  the  various  incoming  nerves  together  and 
connect  them  with  the  various  outgoing  nerves,  somewhat 
after  the  manner  of  the  central  switchboard  in  a  telephone 
exchange.  The  incoming  and  outgoing  nerves  and  the  brain, 
taken  together,  make  up  the  nervous  system,  which  is  the  spe- 
cial organ  of  mental  life. 

The  mental  interplay  between  man  and  his  environment  is 
always  by  means  of  receptor  organs,  nerves,  and  motor 
organs;  and  of  these  the  nerves  (particularly  the  brain)  are 
the  most  mportant  part.  In  studying  psychology  we  have 
to  investigate  not  merely  feelings,  thoughts,  actions,  and  the 
like,  but  the  nervous  system  with  its  receptor  and  motor  con- 
nections; we  must  study  what  takes  place  in  these  organs 
when  one  feels  and  thinks  and  acts. 

The  operation  of  the  nervous  system  in  human  life  may  be 
illustrated  as  follows:  Suppose  a  baseball  fielder  sees  a  ball 
coming  toward  him  through  the  air  and  raises  his  hands  to 
catch  it.     [Fig.  2.]    FifTst,  his  eyes  receive  the  visual  impres- 

etc,  are  part  of  the  processes  of  bodily  growth  and  maintenance  and  do  not 
belong  to  psychological  study. 

*  There  are  also  short-cut  connections  below  the  brain.     See  ch.  ii. 


THE  FIELD  OF  PSYCHOLOGY 


[CH.  I 


sion  of  the  ball.  Then  the  nerves  from  the  eyes  convey  an 
impulse  to  his  brain.  From  the  brain  a  motor  impulse  is 
conveyed  through  other  nerves  to  the  muscles  of  his  arm  and 
hand.     Finally,  as  a  result  of  these  motor  impulses,  the 

muscles   are  contracted    in 


-..St: 


©---.^      c*  *.     such  a  way  that  his  hand  is 

raised  to  intercept  the  ball. 
The  actions  of  animals 
are  due  to  a  similar  system 
of  receptor  organs,  nerves, 
and  muscles.  A  dog  follows 
a  trail  because  the  scent 
affects  his  nostrils.  A  bird 
flies  away  because  the  sound 
of  the  hunter's  footsteps  af- 
fects its  ears.  In  every  case 
the  impression  is  conveyed 
from  some  receptor  organ 
by  means  of  nerves  which 
finally  end  in  some  motor 
organ,  producing  the  action. 
Definitions. — Various  def- 
initions of  psychology  are 
given  in  different  text-books. 
Psychology  is  often  defined 
as  the  science  of  conscious 
phenomena,  which  means 
the  study  of  feehng,  think- 
ing, and  the  like.  Some  of 
the  newer  books  define  psychology  as  the  science  of  behavior, 
which  means  the  study  of  how  human  beings  and  other  crea- 
tures act.  Both  of  these  definitions  are  correct  so  far  as  they 
go.  But  each  tells  only  a  part  of  the  story  —  and  very  dif- 
ferent parts  at  that.  It  is  perhaps  better  to  call  psychology 
the  science  of  mental  life;  but  this  definition  is  not  altogether 


Fio.  2.  —  Seeing  and  Acting 

St.  =  stimulus;  light  waves  from  the  ball. 
R  =  receptors;  the  eyes.  S  =  sensory  nerves, 
running  from  eyes  to  brain.  C  =  center  of 
nervous  system;  the  brain.  M  =  motor  nerves, 
running  from  brain  to  arm.  E  =  effectors  or 
motor  organs;  muscles  of  arm  and  hand. 


CH.  i]  DEFINITIONS  5 

satisfactory,  because  it  does  not  explain  what  is  meant  by 
mental  life.  In  this  book  we  shall  adopt  the  following  defi- 
nition, which  is  reached  by  putting  together  the  results  of 
our  previous  discussion: 

Psychology  is  the  science  which  deals  with  the  facts  and  events 
arising  out  of  the  interaction  between  a  creature  and  its  environ- 
ment by  means  of  receptors,  nervous  system,  and  effectors.^ 

This  book  is  concerned  especially  with  the  mental  life  of 
man;  and  in  human  beings  certain  phases  of  mental  life  are 
far  more  developed  than  in  other  creatures.  Thinking  and 
willing  are  distinctly  human  affairs;  and  we  can  study  many 
other  mental  events  more  closely  in  ourselves  than  we  can  in 
lower  animals.  This  is  particularly  true  o{  feeling,  perceiving y 
and  even  emotion.  In  human  psychology  it  is  important  to 
emphasize  these  mental  facts,  —  experiences,  they  are  called: 

Human  psychology  is  the  science  which  deals  with  the  inter- 
action between  man  and  his  environment  by  means  of  the  nervous 
system  and  its  terminal  organs^  together  with  the  mental  events 
which  accompany  this  interplay. 

Problems  of  Psychology.  —  These  definitions  indicate  at 
the  outset  the  fields  of  study  that  are  not  included  in  psychol- 
ogy. It  is  evident  that  mathematics  and  astronomy,  physics 
and  chemistry,  are  not  directly  concerned  with  '  interactions 
between  creatures  and  their  surroundings  by  means  of  the 
nervous  system.' 

In  the  second  place,  psychology  is  not  especially  interested 
in  the  general  problems  of  animal  and  plant  life  which  biology 
studies.  It  is  not  diflScult  to  distinguish  between  biological 
Ufe  and  mental  life.  Biological  life  depends  upon  assimilating 
food  and  throwing  off  the  waste  products.  The  organs  which 
perform  these  processes  are  the  mouth,  stomach,  and  intes- 
tines, rather  than  the  nervous  system.     Biology  studies  such 

'  Effectors  are  muscles  and  other  organs  (such  as  glands)  by  which  the 
creature  produces  an  effect. 

*  The  terminal  organs  of  the  nervous  system  include  both  the  receptors 
and  effectors. 


6  THE  FIELD  OF  PSYCHOLOGY  [ch.  i 

processes  as  nutrition  and  growth  and  reproduction.  These 
processes  are  for  the  most  part  chemical  and  other  changes 
within  the  body  itself.  They  are  quite  different  from  the 
events  of  menial  life  which  psychology  studies. 

Biology  is  interested  in  finding  out,  (1)  How  plants  and 
animals  keep  alive;  (2)  How  they  grow  from  the  egg  to 
maturity;  (3)  How  they  repair  injuries;  (4)  How  they  pro- 
duce offspring  like  themselves. 

Psychology  is  interested  in  studying,  (1)  What  sorts  of 
impressions  living  creatures  get  from  the  world  around  them; 
(2)  How  they  get  this  information;  (3)  How  they  use  it  so  as 
to  move  and  act  on  their  surroundings;  (4)  How  social 
creatures  like  man  communicate  and  work  with  one  an- 
other. 

Interactions  between  the  creature  and  his  surroundings 
take  place  continually.  In  human  life  they  are  much  more 
important  concerns  than  feeding  and  growing.  Interplay 
with  the  environment  is  involved  in  all  our  pursuits  —  our 
studies,  business,  sports,  and  home  life.  Man  has  devised 
countless  ways  of  protecting  himself  against  the  dangers  and 
rigors  of  his  environment.  He  makes  clothing  and  dresses 
himself.  He  builds  houses.  He  plants  crops,  raises  herds, 
and  catches  fish.  He  has  worked  out  an  elaborate  system  of 
distributing  these  food  products  and  other  useful  material. 
All  this  has  been  accomplished  by  means  of  the  nervous  system. 
Psychology  is  concerned  with  discovering  how  all  such  actions 
are  performed. 

Human  psychology,  then,  deals  with  the  following  ques- 
tions: 

What  sorts  of  information  do  we  get  from  the  outside  world  and  from 
our  own  body? 

How  is  this  information  jmt  together  into  perceptions,  thoughts,  desires, 
emotions,  and  other  mental  experiences? 

How  do  we  remember  things  and  how  do  we  learn  to  do  things  in  the  right 
way? 

How  do  human  beings  develop  a  social  life,  by  means  of  which  they  talk 
and  work  together? 


CH.  i]  PROBLEMS  7 

How  do  men  come  to  get  such  control  of  their  environment  that  they 
master  it  and  use  it  for  their  own  ends? 

What  is  man's  personality,  which  receives  this  information  about  the 
world  and  puts  it  together  and  uses  it? 

These  are  the  main  problems  of  human  psychology;  but 
each  of  them  includes  many  lesser  ones.  For  instance,  learn- 
ing to  play  golf  is  a  very  different  thing  from  learning  to 
control  your  temper;  and  still  different  is  learning  how  to 
manage  a  business  or  how  to  bring  up  a  family.  But  we  shall 
find  that  there  are  certain  general  rules  or  laws  which  apply 
to  all  kinds  of  learning. 

Collecting  the  Facts.  —  The  first  step  in  any  science  is  to 
gather  a  great  mass  of  facts.  In  all  the  sciences  that  study 
nature  this  is  done  by  observing  carefully  the  ways  in  which 
nature  works.  There  is  always  a  temptation  to  guess  at 
things  —  to  imagine  that  things  work  in  a  certain  way,  be- 
cause this  seems  the  most  Ukely  way  for  them  to  act.  For 
instance,  men  used  to  think  that  a  heavy  body  falls  faster 
than  a  light  one.  For  a  long  time  no  one  tried  it  out.  Fi- 
nally, Galileo  thought  it  safer  to  observe  than  to  guess.  He 
dropped  two  balls,  a  heavy  and  a  light  one,  from  the  Leaning 
Tower  of  Pisa; —  and  both  reached  the  ground  at  the  same 
time.  The  notion  which  every  one  had  taken  for  granted 
proved  to  be  wrong. 

In  psychology  we  are  especially  apt  to  use  the  guesswork 
plan,  because  the  facts  are  so  much  a  part  of  our  e very-day 
life  that  we  think  we  can  see  them  without  looking.  Every- 
body who  has  not  studied  psychology  thinks  he  has  just  five 
senses  —  with  perhaps  a  '  mysterious  sixth  '  called  intuition. 
But  when  psychologists  began  to  observe  carefully,  they 
found  that  man  has  several  other  senses  which  had  been  over- 
looked. We  know  now  that  there  are  at  least  eleven  senses, 
and  possibly  more.  The  first  rule  in  psychology  (as  in  every 
study  of  nature)  is  to  observe  carefully. 

Each  science  has  its  own  special  methods  of  observing  its 


8  THE  FIELD  OF  PSYCHOLOGY  [ch.  i 

facts.  Psychology  uses  three  different  kinds  of  observation*. 
(1)  observing  ourselves,  (2)  observing  the  behavior  of  others, 
and  (3)  observing  the  nervous  system  and  its  terminals. 

(1)  Self-observation,  which  is  also  called  introspection, 
means  the  study  of  our  own  individual  experiences.  At  the 
present  moment  you  see  this  book  and  other  things  around 
you.  You  are  thinking  perhaps  about  psychology  or  perhaps 
about  your  dinner.  You  may  be  remembering  something 
that  happened  to  you  yesterday.  Maybe  you  have  a  tooth- 
ache, or  are  angry,  or  are  drumming  on  the  table  with  your 
fingers.  These  and  other  experiences  are  events  in  your  own 
mental  life;  by  paying  close  attention  to  them  you  gather 
material  for  the  study  of  psychology.  Self-observation 
means  examining  your  own  experiences  carefully.  By  strict 
attention  you  often  observe  experiences  that  would  otherwise 
escape  notice;  —  the  touch  of  your  clothes  against  the  skin, 
the  tingle  in  one  finger,  the  throbbing  of  the  heart,  a  faint 
noise  in  the  distance. 

Self-observation  is  the  most  important  method  in  human 
psychology.  It  can  also  be  used  indirectly.  Your  friends 
tell  you  their  experiences;  this  enables  you  to  get  at  certain 
mental  facts  which  do  not  come  into  your  own  life,  so  that 
you  can  check  up  on  your  own  observations.  In  animal 
psychology  this  method  cannot  be  used  either  directly  or 
indirectly,  because  even  the  highest  animals  do  not  *  observe 
their  experiences  carefully,'  nor  can  they  report  them  to  the 
psychologist. 

(2)  Observation  of  Behavior  is  the  study  of  the  way  in 
which  human  beings  and  animals  act.  Notice  a  group  of 
men  listening  to  a  lecture.  One  man  turns  his  right  ear 
slightly  toward  the  speaker.  Another  wrinkles  his  forehead 
and  screws  up  his  mouth.  A  third  scratches  his  head  and 
twirls  his  mustache.  These  are  different  attention-attitudes. 
When  you  observe  them  carefully  you  are  using  the  behavior 
method  of  studying  psychology.     Notice  what  the  fielders 


CH.  i]  COLLECTING  THE  FACTS  9 

do  in  a  baseball  game  when  the  batter  makes  a  hit.  Their 
actions  are  different,  but  each  act  is  a  form  of  behavior.  All 
behavior  is  the  result  of  some  impression  through  the  receptor 
organs.  The  lecturer's  words  or  the  flying  ball  start  the 
activity;  they  are  called  stimuli.  The  attitudes  and  actions 
which  follow  are  called  responses. 

It  is  difficult  to  observe  one's  own  behavior.  If  you  are 
fielding  a  ball  you  scarcely  have  time  to  observe  the  way  you 
are  doing  it;  your  attention-attitudes  during  a  lecture  usually 
escape  your  own  observation.  On  the  other  hand  it  is  easy, 
after  a  certain  amount  of  training,  to  study  with  precision 
the  behavior  of  others.  Behavior  study  is  even  more  im- 
portant in  animal  than  in  human  psychology. 

(3)  Observation  of  the  Nervous  System  and  its 
Terminals  is  used  to  supplement  the  two  other  methods. 
It  means  examining  the  brain  to  find  out  how  the  various 
nerves  run  into  it  and  out  from  it  and  how  they  are  con- 
nected together.  Where  certain  parts  of  the  brain  are  de- 
stroyed by  disease,  we  find  disturbances  of  the  mental  life. 
If  one  region  of  the  brain  is  affected  the  man  loses  the  sense 
of  touch;  destruction  of  another  region  means  loss  of  speech. 
Paralysis  of  one  side  of  the  body  is  due  to  injury  of  certain 
regions  in  the  opposite  side  of  the  brain. 

This  method  is  carried  further  in  animal  study  by  cutting 
out  definite  regions  of  the  brain  and  noticing  the  effect  on  the 
animal's  behavior.  The  results  of  this  animal  work  are  ap- 
plied to  human  psychology  in  so  far  as  the  brains  correspond. 
But  the  human  brain  is  exceedingly  complicated;  animal  ex- 
periments do  not  help  us  in  studying  the  higher  mental  proc- 
esses, which  occur  only  in  man. 

Another  way  of  observing  the  nervous  system  is  by  making 
experiments  on  single  nerves  and  nerve  fibers,  in  order  to 
discover  the  nature  of  the  nerve  current  and  the  laws  of  nerve 
activity.  This  is  done  by  stimulating  some  nerve  with  an 
electric  current  and  noting  what  sensation  or  movement 


10  THE  FIELD  OF  PSYCHOLOGY  [ch.  i 

occurs.  K  electrodes  be  placed  on  your  forehead  and  the 
back  of  your  neck,  and  a  weak  alternating  current  be  passed 
through  the  circuit,  you  will  see  flashes  of  violet  light.  Other 
electric  stimulation  causes  twitching  of  the  fingers. 

Examination  of  the  receptor  organs  also  gives  some  facts 
which  bear  on  psychology.  The  eye  and  the  ear  are  very 
intricate  organs.  A  study  of  their  structure  helps  us  to 
understand  some  of  the  peculiarities  of  sight  and  hearing. 

Observation  of  the  nervous  system  has  not  given  as  much 
useful  information  as  one  would  expect,  because  in  such  ex- 
periments we  observe  only  part  of  the  effects  that  occur  in 
real  life.  Little  is  known  as  yet  about  the  real  nature  of  the 
nerve  current  in  the  living  body.  For  these  reasons  the 
method  of  nerve-observation  is  useful  only  for  checking  up 
some  of  the  results  obtained  by  the  two  other  methods. 

Observation  and  Experiment.  —  We  have  used  the  word 
observation  in  speaking  of  these  three  methods.  But  in  each 
case  the  psychologist  is  often  able  to  make  use  of  experiment. 
The  distinction  between  observation  and  experiment  is  this: 
in  observation  we  watch  the  way  in  which  things  happen  by 
themselves,  while  in  experiment  we  arrange  the  conditions 
beforehand. 

If  we  watch  some  one  learning  to  typewrite,  and  notice  his 
mistakes  and  how  he  improves,  we  are  getting  at  the  facts  by 
observation.  But  if  we  give  him  a  page  to  copy  and  measure 
the  time  it  takes  him  to  do  it  and  count  the  number  of  errors, 
our  observation  becomes  an  experiment.  We  tell  him  to 
practice  an  hour  a  day,  and  at  the  end  of  each  day  we  time 
him  for  a  single  page;  then  we  have  an  experimental  measure 
of  his  daily  improvement.  One  of  the  experiments  on  color 
sensations  consists  in  giving  a  person  a  great  many  bits  of 
wool  of  different  hues  and  shades  and  asking  him  to  match 
them.  The  results  will  show  how  many  colors  he  can  dis- 
criminate and  whether  or  not  he  is  color  blind. 

Experiment  is  more  satisfactory  than  observation,  because 


CH.  i]      OBSERVATION  AND  EXPERIMENT  II 

it  enables  us  to  get  at  important  facts  much  more  quickly. 
It  may  take  a  long  time  to  discover  that  a  certain  person  is 
color  blind  if  we  merely  observe  his  actions,  while  an  experi- 
ment in  sorting  out  colored  wools  will  usually  settle  the  ques- 
tion at  once.  On  the  other  hand  it  is  not  always  practicable 
to  use  experimentation.  When  we  try  to  study  our  own  ex- 
periences, we  generally  find  that  we  cannot  arrange  the  con- 
ditions beforehand  without  spoiling  the  effect.  For  instance, 
it  is  almost  impossible  to  make  yourself  angry  deUberately. 
In  studying  anger  in  yourself,  you  must  wait  till  something 
unexpected  happens  which  arouses  your  anger,  and  then  ob- 
serve it  —  if  you  are  enough  of  a  psychologist  to  do  so. 

The  study  of  the  human  nervous  system  is  almost  entirely 
a  matter  of  observation,  because  we  know  of  no  way  to  take 
nerves  out  from  the  human  body  or  to  investigate  the  brain 
of  a  living  man  without  injuring  him  seriously.  In  the  study 
of  our  own  experiences,  observation  and  experiment  are  used 
about  equally. 

In  applying  the  behavior  method,  experiment  can  almost 
always  be  used,  and  its  results  are  much  more  satisfactory 
than  mere  observation.  The  wool-sorting  test  for  color 
blindness  is  an  experiment  which  uses  the  behavior  method; 
the  person  tested  arranges  the  wools  in  groups  or  series  in- 
stead of  describing  what  he  sees. 

Most  of  the  work  in  the  human  psychological  laboratory  is 
experimental  —  a  kind  of  experiment  in  which  human  be- 
havior plays  a  very  important  part.  It  would  be  diflScult  for 
any  one  to  determine  by  mere  observation  just  how  long  it 
takes  him  to  think  or  to  recognize  a  word;  but  this  is  measured 
quite  accurately  in  the  laboratory  by  experiments  on  human 
behavior.  An  electric  circuit  is  arranged  which  starts  a  clock 
(called  the  chronoscope)  the  instant  a  shutter  falls,  and  stops 
the  clock  the  instant  the  observer  presses  a  key.  Behind  the 
shutter  a  word  is  placed,  and  then  the  shutter  is  released  by 
the  experimenter.     The  person  experimented  upon  sees  the 


12  THE  FIELD  OF  PSYCHOLOGY  [ch.  i 

word,  and  as  soon  as  he  recognizes  it  he  presses  the  key.  The 
clock  is  running  from  the  instant  the  word  comes  in  sight  to 
the  instant  the  key  is  pressed;  it  records  time  in  thousandths 
of  a  second.  This  enables  the  experimenter  to  measure  the 
time  required  to  recognize  the  word.* 

After  we  have  arranged  the  conditions  of  an  experiment, 
we  must  watch  the  events  carefully  and  Tnust  not  interfere 
with  the  way  they  work  themselves  out.  We  are  not  free  to 
arrange  results  to  suit  ourselves.  An  experiment  means 
putting  a  definite  question  to  nature.  It  is  for  nature  to 
answer  the  question,  and  we  are  bound  to  accept  the  answer 
given,  even  though  it  is  not  what  we  had  expected.  There  is 
often  a  great  temptation  to  amend  the  results  so  as  to  bring 
them  out  as  we  think  they  ought  to  be.  But  this  is  not  deal- 
ing fairly  with  nature.  If  we  doubt  the  correctness  of  the 
results,  the  only  proper  course  is  to  repeat  the  experiment^ 
taking  care  to  avoid  any  errors  that  may  have  occurred  the 
first  time  in  arranging  the  conditions  or  making  the  measure- 
ments. 

We  find,  then,  that  psychology  uses  three  methods  to  col- 
lect the  facts:  (1)  Self-study,  (2)  Behavior  study,  and  (3) 
Nerve  study;  and  in  connection  with  each  of  these  methods 
it  may  proceed  either  (a)  by  observation  of  events  as  they 
occur  in  nature,  or  (6)  by  experiment  —  that  is,  by  arranging 
the  conditions  so  as  to  bring  out  certain  facts. 

Divisions  of  Psychology.  —  We  have  already  noticed  the 
distinction  between  human  and  animal  psychology.  There 
are  a  number  of  other  branches  of  the  science  which  cover 
special  fields  of  study.  In  the  first  place,  the  name  Human 
Psychology,  or  General  Psychology,  is  usually  appUed  to  the 
study  of  the  normal,  adult  human  being.  This  is  distin- 
guished from  the  study  of  the  human  child. 

*  We  know  how  fast  light  travels,  and  about  how  fast  the  nerve  impulse 
travels  from  the  eye  to  the  brain  and  from  the  brain  to  the  finger.  This 
transmission  time  must  be  taken  into  account.  The  chronoscope  is  shown 
in  Fig.  79,  p.  S09. 


c«  i]  BRANCHES  OF  THE  SUBJECT  IS 

The  object  of  Child  Psychology  is  to  discover  how  each 
different  sort  of  experience  originates  in  childhood  and  de- 
velops to  the  precise  form  found  in  adult  beings.  For  in- 
stance, we  may  study  the  beginnings  of  speech  in  the  child 
and  trace  its  gradual  improvement;  or  we  may  study  the 
child's  expression  of  anger  and  other  emotions,  and  observe 
how  they  become  suppressed  and  altered  in  later  life.  Simple 
habits,  such  as  buttoning  clothes,  tying  bow-knots,  lacing 
shoes,  are  learned  by  degrees;  the  first  attempts  are  awkward 
failures;  child  psychology  seeks  to  trace  the  growth  of  these 
habits  from  their  very  start. 

Animal  Psychology,  also  called  Comparative  Psychology,  is 
interested  in  this  same  problem  of  mental  growth  on  a  larger 
scale.  In  animal  psychology  we  study  the  evolution  of  men- 
tal life  from  the  lowest  species  to  the  highest.  It  is  found 
that  the  amoeba  is  not  capable  of  learning  by  practice.  The 
crayfish  can  learn  a  little.  If  we  place  a  crayfish  in  a  simple 
maze '  with  food  at  the  other  end,  after  repeated  practice  he 
will  learn  the  proper  path  to  the  food;  he  gradually  makes 
fewer  mistakes  and  reaches  the  food  in  a  shorter  time.  Ani- 
mals higher  up  in  the  scale  of  evolution  learn  more  quickly. 
It  is  found  that  the  white  rat  is  very  intelligent  and  can  learn 
the  solution  of  rather  compUcated  mazes.  Animal  psychology 
also  studies  the  growth  of  sight,  hearing,  and  other  senses, 
following  the  course  of  biological  evolution  from  lower  to 
higher  species. 

Another  branch  of  the  subject  is  Abnormal  Psychology. 
This  investigates,  among  other  things,  the  changes  in  mental 
life  due  to  diseases  of  the  brain  or  other  disorders.  There 
are  many  types  of  insanity,  which  come  from  various  causes. 
Some  show  themselves  in  mental  depression  or  wild  excite- 
ment; other  cases  are  marked  by  strange  delusions;  others  by 
inability  to  speak  (aphasia). 

It  is  important  to  distinguish  between  disordered  minds  and 
1  See  Fig.  73,  p.  252. 


14  THE  FIELD  OF  PSYCHOLOGY  [ch.  i 

undeveloped  minds.  The  class  of  individuals  called  idiots, 
imbeciles,  and  weak-minded  are  not  insane;  their  minds  are 
merely  undeveloped.  They  are  like  children  in  their  ways  of 
thinking  and  acting,  though  their  bodily  growth  in  other 
respects  may  be  normal.  The  study  of  mental  retardation, 
or  backwardness,  is  a  division  of  abnormal  psychology  quite 
distinct  from  insanity.' 

Physiological  Psychology  makes  a  special  examination  of 
the  nervous  system.  It  studies  the  different  parts  of  the 
brain,  traces  the  course  of  nerves  to  and  from  the  brain,  de- 
termines the  special  activity  of  nerves  and  receptor  organs, 
and  investigates  the  relation  of  nervous  activity  to  mental 
life.  Its  findings  are  used  by  psychology  to  throw  light  on 
mental  processes  and  behavior. 

Experimental  Psychology  is  the  name  given  to  the  experi- 
mental study  of  human  mental  hfe  in  the  laboratory.  It  is 
especially  concerned  with  measuring  the  events  instead  of 
merely  describing  them.  For  instance,  experimental  jpsy- 
chology  tries  to  discover  just  how  many  colors  can  be  dis- 
tinguished; how  long  it  takes  to  memorize  a  poem,  and  how 
rrvuch  we  forget  in  a  day  or  a  week;  how  quickly  one  idea  sug- 
gests another  idea,  and  what  sorts  of  associations  are  most 
jrequent  between  two  ideas;  the  rate  at  which  we  improve 
in  learning  new  habits,  as  shown  by  our  speed  in  performing 
the  act  or  by  the  decrease  in  the  number  of  our  mistakes. 

Physiological  and  experimental  psychology  are  really  parts 
of  the  general  branch  called  human  psychology.  We  sepa- 
rate them  for  special  study  because  they  involve  the  use  of 
delicate  instruments  and  require  special  training  on  the  part 
of  the  student.  Many  of  their  results  are  included  in  text- 
books on  human  psychology. 

^  The  study  of  blindness,  deafness,  and  other  peculiarities  which  depend 
on  defective  receptors,  might  be  included  under  abnormal  psychology. 
But  these  defects  do  not  make  the  individual  'pathological,'  like  insanity 
and  mental  retardation;  so  they  are  generally  studied  in  connection  with 
normal  psychology. 


CH.  i]  BRANCHES  OF  THE  SUBJECT  15 

In  the  same  way  we  may  pick  out  any  topic  for  special 
study  and  regard  it  as  a  division  of  psychology.  The  'psy- 
chology oj  religion  is  a  special  study  of  religious  experiences; 
fsychofhysics  is  an  experimental  study  of  the  relation  be- 
tween stimuli  and  sensations;  the  psychology  of  play  investi- 
gates the  origin,  development,  and  varieties  of  play  in  man 
or  in  different  species  of  animals. 

Social  Psychology  studies  the  events  which  occur  when  one 
being  acts  upon  another,  or  when  a  group  of  individuals  act 
together.  For  instance,  imitation  means  that  one  person 
copies  the  actions  of  another;  the  second  influences  the  first  — 
it  may  be  quite  unconsciously.  Teaching  means  that  one 
individual  tries  to  arouse  certain  thoughts  in  another.  Speak- 
ing and  writing  are  social  events;  they  are  generally  directed 
toward  some  one  else.  Our  moral  acts  depend  on  our  recog- 
nition that  other  human  beings  have  feelings  Uke  our  own. 
In  a  crowd  and  in  a  community  there  is  always  a  tendency  for 
individuals  to  think  along  the  same  lines  and  to  act  more  or 
less  as  a  unit;  an  individual  acts  differently  in  a  crowd  than 
when  he  is  alone. 

All  these  are  examples  of  the  kinds  of  events  which  social 
psychology  studies.  Social  psychology  should  not  be  con- 
fused with  sociology.  Sociology  studies  social  and  industrial 
relationships  of  every  sort,  while  social  psychology  is  con- 
cerned only  with  actions  and  behavior  which  are  accomplished 
by  means  of  the  nervous  system. 

Applied  Psychology  is  not  a  division  of  psychology  like 
those  just  discussed;  it  means  the  art  of  using  in  practical 
ways  the  results  obtained  from  psychology.  After  we  have 
discovered  how  the  human  mind  works,  certain  tests  may  be 
arranged  by  which  we  can  size  up  any  individual  mind.  For 
instance,  if  we  know  what  sort  of  mental  processes  are  needed 
in  a  certain  occupation,  we  may  devise  tests  for  picking  out 
the  most  promising  persons  from  among  the  candidates  who 
are  seeking  the  position.     Mental  tests  are  used  to  discover 


16  THE  FIELD  OF  PSYCHOLOGY  [ch.  i 

whether  a  given  person  has  the  mental  quaUfications  to  make 
a  good  salesman  or  a  good  telephone  operator.  Other  kinds 
of  tests  are  used  to  indicate  whether  a  child  belongs  in  the 
same  school-class  as  those  of  his  own  age,  or  should  be  placed 
in  a  higher  or  lower  class.  The  degree  of  mental  retardation 
in  morons  and  imbeciles  is  determined  in  a  similar  way.' 

Another  use  of  appUed  psychology  is  in  connection  with 
advertising.  One  advertisement  will  attract  more  notice 
than  another;  some  advertisements  unintentionally  repel  the 
average  man.  It  is  the  task  of  applied  psychology  to  find 
out  what  sorts  of  advertisements  appeal  to  the  average  human 
being  —  to  lay  down  laws  about  what  to  do  and  what  to 
avoid  in  advertising.  These  laws  depend  on  a  knowledge  of 
human  nature;  they  are  applications  of  principles  which  have 
been  discovered  by  the  study  of  psychology.  In  general, 
appUed  psychology  is  the  appUcation  of  psychological  princi- 
ples to  practical  problems  of  Ufe. 

The  important  divisions  of  psychology,  then,  are  as  follows: 

Human  or  general  psychology  (study  of  the  normal  adult^ 

Child  psychology 

Animal  or  comparative  psychology 

Abnormal  psychology  (insanity  and  mental  retardation) 

Physiologi(^'psychology    L^^ii^  studies 

l!<xpenmental  psychology  ) 

Social  psychology 

Applied  |>sychology  (practical  applications) 

Summary  and  Outline.  —  Psychology  is  the  science  that 
studies  the  interaction  between  human  beings  and  their  en- 
vironment which  occurs  by  means  of  the  nervous  system. 
Like  every  other  science,  psychology  gets  its  faxits  by  obser- 
vation and  experiment.  There  are  three  methods  of  observ- 
ing psychological  facts:  observing  our  own  experiences,  ob- 
serving the  behavior  of  others,  and  observing  the  workings 
of  the  nervous  system. 

*  A  moron  is  less  deficient  mentally  than  an  imbecile.  The  word  was 
coined  as  the  result  of  mental  tests,  which  showed  that  in  addition  to  idiocy 
and  imbecility  there  is  a  third,  superior  grade  of  mental  retardation. 


CH.  i]  SUMMARY  AND  OUTLINE  17 

Besides  the  study  of  human  psychology  there  are  several 
other  fields  of  psychological  investigation,  such  as  animal, 
child,  and  social  psychology.  Applied  psychology  is  the 
application  of  psychological  laws  and  principles  to  practical 
problems  in  Ufe. 

In  this  book  we  are  to  study  human  psychology.  How  shall 
we  go  about  it?  By  our  definition,  human  psychology  is  the 
attempt  to  discover  —  systematically  —  how  men  are  in- 
fluenced by  their  surroundings;  what  sorts  of  experiences 
occur  in  human  life;  how  men  react  upon  the  world  around 
them;  how  human  character  and  personality  are  formed. 
When  we  study  these  problems  we  must  begin  at  the  founda- 
tion. You  will  not  understand  the  meaning  of  personality 
unless  you  first  examine  the  various  kinds  of  experiences  that 
enter  into  its  make-up.  Speech  and  voluntary  action  cannot 
be  explained  without  some  knowledge  of  the  nervous  system 
and  how  it  works. 

The  objection  to  most  attempts  at  psychology  by  untr^ned 
writers  is  that  they  generally  begin  at  the  wrong  end.  Most 
of  the  popular  articles  on  metaphysical  psychology,  new 
thought,  mental  concentration,  and  the  like,  treat  mind  as  a 
simple  unit  instead  of  a  composition  or  product.  They  com- 
mence with  the  universe  instead  of  the  atom.  If  we  wish  to 
understand  mental  life  and  human  nature  we  must  start  at 
the  bottom  and  work  up. 

The  first  step  is  to  study  the  nervous  system  (ch.  ii)  and 
how  it  works  (ch.  iii),  since  all  our  thinking  and  acting  de- 
pend on  nerve  connections.  Then  we  examine  the  receptors, 
and  the  sensations  which  we  get  through  their  operation 
(chs.  iv,  v).    This  furnishes  the  foundation  for  the  science. 

Man's  conscious  life  is  made  up  of  experiences,  and  each 
particular  experience  is  a  union  of  many  separate  sensations. 
After  we  have  made  a  survey  of  the  senses,  we  are  in  a  posi- 
tion to  examine  their  relation  to  conscious  Ufe  (ch.  vi).  The 
next  step  is  to  study  the  different  kinds  of  experiences  that 


18  THE  FIELD  OF  PSYCHOLOGY  [ch.  i 

enter  into  man's  daily  life  (chs.  vii-xiii).  But  mental  life  in- 
cludes actions  as  well  as  experiences.  So  in  studying  certain 
kinds  of  human  experience  we  have  to  examine  the  various 
forms  of  behavior,  such  as  instinct  and  intelligence  (chs.  x,  xi). 

Thus  far  our  study  is  confined  to  single,  definite  experi- 
ences and  actions.  We  now  go  further  and  examine  the  suc- 
cession of  experiences  which  change  from  moment  to  moment 
(ch.  xiv).  Finally,  we  may  trace  the  process  by  which  man's 
personality  is  built  up  out  of  these  successive  experiences  and 
how  he  gradually  gains  control  over  his  actions  and  becomes 
master  of  himself  and  his  sm-roundings  (chs.  xv,  xvi). 

This  is  a  systematic  order  of  studying  the  subject.  One 
step  leads  to  the  next.  It  avoids  the  popular  error  of  as- 
suming that  such  complex  things  as  mind,  will,  and  intelli- 
gence are  simple  and  fundamental. 

Practical  ExERasEs: 

1.  Report  briefly  (1)  some  feeling  you  have  had  lately;  (2)  some  memory 
you  have  recently  recalled;  (3)  some  thought;  (4)  some  action  you  have 
just  performed.  Bring  out  as  far  as  possible  the  diflFerence  between 
these  four  experiences. 

2.  Take  two  recent  instances  in  which  the  environment  has  affected  you 
and  then  you  have  acted  on  the  environment.  Describe  the  whole 
chain  of  events  as  far  as  you  can  observe  them. 

3.  Say  the  word  "Man"  out  loud.  Now  describe  this  occurrence  (your 
speaking)  in  two  diflFerent  ways:  (1)  As  you  observe  yourself  talking; 
(2)  As  another  person  would  observe  you  doing  it.  Compare  the  two 
descriptions. 

4.  Observe  a  young  child's  speech  or  handwriting;  compare  it  with  that 
of  an  adult  and  point  out  any  evidence  of  mental  immaturity  which 
the  comparison  brings  out. 

6.  Report  some  instance  where  you  have  been  carried  away  by  the  in- 
fluence of  a  crowd.  Describe  how  your  actions  and  feelings  have  been 
influenced,  and  explain  the  reason  so  far  as  possible. 

[Exercise  1  is  on  the  different  sorts  of  experience;  2  is  on  our  relation 
to  the  environment;  3  is  on  the  distinction  between  self-observation  and 
behavior-observation;  4  is  on  child  psychology;  5  is  on  social  psychol- 
ogy.    See  p.  391  for  Suggestions  in  performing  the  exercises.] 

Rbfebences: 
On  definitions  of  psychology:  Wm.  James,  Principles  of  Psychology,  ch.  1; 
J.  B.  Watson,  Psychology,  ch.  1. 


CHAPTER  II 
STRUCTURE  OF  THE  NERVOUS  SYSTEM 

Cells. — The  human  body  is  composed  of  a  vast  number  of 
units  called  cells.  These  cells  are  formed  of  substances  which 
are  chemically  very  much  alike,  and  every  living  cell  contains 
a  nucleus,  which  is  essential  to  its  life.  There  are  many  kinds 
of  cells  which  differ  in  shape,  degree  of  rigidity,  and  other 
characteristics.  [Fig.  3.]  Each  of  our  bones  is  made  up  of  a 
number  of  bone  cells  united  firmly  together.  Our  blood  con- 
tains a  mass  of  floating  corpuscles,  each  a  separate  cell.  Our 
skin  is  a  network  of  epithelial  cells  which  are  not  so  firmly 
compressed  together  as  the  bone  cells,  and  allow  stretching 
and  other  changes  in  shape.  The  stomach,  heart,  and  other 
internal  organs  are  made  up  of  cells,  each  organ  being  built 
up  of  some  special  sort  of  cell. 

The  nervous  system  and  the  terminal  organs  connected 
with  it  are  formed  in  the  same  way.  Tiie  nerves  are  com- 
posed of  cells  of  a  very  unusual  kind:  they  are  very  long  and 
thin,  like  threads,  so  that  the  name  cell  seems  a  misnomer. 
The  special  receptors  (such  as  the  eye  and  ear)  are  composed 
of  several  different  kinds  of  cells.  The  muscles  are  formed 
of  muscle  cells  joined  together  into  long  bands  or  strips: 
when  a  nerve  impulse  affects  them  each  strip  contracts  and 
the  whole  muscle  is  shortened. 

Our  body  grows  by  the  enlargement  and  splitting  up  of  its 
cells.  When  a  cell  reaches  a  certain  size,  it  divides  by  a  com- 
plicated process  into  two  cells,  each  of  which  is  like  the 
*  parent '  cell.  In  course  of  time  a  cell  may  die,  just  as  a 
living  being  dies.  It  is  then  disposed  of  as  waste  matter,  and 
a  new  cell  (formed  by  the  division  of  some  living  cell  of  the 
same  kind)  takes  its  place.  When  a  man  reaches  maturity 
the  death  of  old  cells  just  about  balances  the  production  (rf 


20    STRUCTURE  OF  THE  NERVOUS  SYSTEM  [cH.n 


new,  so  that  he  ceases  to  grow.  But  man  is  still  able,  until 
late  in  life,  to  restore  sections  of  skin  and  flesh,  and  to  knit 
together  bones  that  have  been  injured. 

Every  living  creature  starts  as  a  single  cell  of  a  special  sort, 
called  a  germ,  cell,  which,  when  it  is  fertilized  by  union  with 

Germ  Cell   Bone.  Celb     Nerve  Cell  Receptor  Cell 

(Retinal  Cone) 


Mu3cle  Cells 


-\ 


J 


epithelial  Cells 


Blood  Cell 


Fig.  8.  —  Different  Kinds  op  Cells 

Some  of  the  principal  cells  which  make  up  the  body;  greatly  enlarged  in  the  drawing.  The 
human  body  contains  many  other  varieties  of  cells. 


CH.  n] 


CELLS 


21 


Oandriltti 


C«ll  Bod 


ColUUral 


another  germ  cell  of  the  opposite  sex,  begins  to  grow  and 
subdivide.  The  cells  first  formed  in  this  growth  process  are 
not  all  alike;  they  are  the  starting-point  for  the  bones,  skin, 
inner  organs,  nerves,  and  other  components  of  the  body. 
As  the  division  of  cells  continues  the  body  gradually  takes 
shape,  and  its  various  parts  begin  to  be  formed. 

The  cells  composing  the  human  nervous  system  develop 
rapidly  in  the  embryo,  and  practically  all  of  them  are  formed 
before  birth.  Their  number  is  astonishingly  great;  there  are 
over  nine  billion  nerve  cells  in  the  outer  layer  (cortex)  of  the 
brain  alone. 

The  Neuron. — The  separate  cells 
which  make  up  the  nervous  system 
are  called  neurons.  In  the  neuron 
the  main  body  of  the  cell,  which 
contains  the  nucleus,  is  very  small 
compared  with  the  rest  of  the  struc- 
ture. The  important  feature  is  a 
long  thread-Uke  fiber  which  pro- 
jects out  from  the  cell-body,  and 
usually  has  several  branches. 

Fig.  4  shows  one  sort  of  neuron, 
in  which  a  long  fiber,  called  the 
axon,  extends  from  the  cell-body  in 
one  direction,  terminating  in  very 
fine  fibrils,  called  the  telodendrion, 
or  endbrush.  The  axon  is  usually 
provided  with  branches,  called  col- 
laterals. At  the  other  end  of  the 
cell-body  there  is  a  larger  network 
of  fibrils,  called  dendrites,  which 
branch  out  like  a  tree.    There  are 

several  other  varieties  of  neuron  [Fig.  5],  in  some  of  which 
the  fibers  extend  in  both  directions  from  the  cell-body.' 

^  In  both  Figs.  4  and  5  the  thickness  of  the  fibers  is  exaggerated,  otherwise 


TalodandriON 


Fig.  4.  —  The  NExmoN  and 
ITS  Pabts 


22    STRUCTURE  OF  THE  NERVOUS  SYSTEM  [ch.ii 

The  length  of  the  axon  varies  considerably.  Some  axons 
are  very  short;  they  belong  to  neurons  which  link  together 
two  neighboring  neurons  in  the  spinal  cord  within  the  back- 


FiQ.  5.  —  Vabiotts  Types  of  Neuhons 

Six  di£Ferent  sorts  of  neurons.  Notice  the  small  size  of  the  cell-body  and  great  length  of  the 
axon.  In  the  drawing  the  thickness  of  axon  and  collaterab  is  exaggerated,  and  the  finer  fibrils 
do  not  show.     [From  Thomdike.] 


bone.  There  are  other  neurons  whose  axon  fibers  are  more 
than  two  feet  in  length,  extending  all  the  way  from  the  toes 
to  the  spinal  cord.  The  point  to  remember  especially  about 
the  neuron  is  that  it  is  a  line  of  conduction  or  pathway  aloi^g 
whichnierve  impulses,  travel. 

they  could  not  be  seen  in  the  picture;  in  Fig.  4  the  size  of  the  cell-body  is 
drawn  too  large  compared  with  the  projections,  so  as  to  show  the  nucleus. 


CH.  n] 


THE  SYNAPSE 


28 


The  Synapse.  —  In  the  general  arrangement  of  the  nervous 
system  each  neuron  connects  up  end  to  end  with_ajiotber 
neuron.^  A  series  of  neurons  jomed  together  in  this  way  form^ 
a  chain  or  circuit  which  extends  from  the  eye  or  ear  or  some 
other  receptor  to  the  brain,  and  from  the  brain  to  some  muscle 
or  gland;  every  receptor  is  the  starting-point  of  a  nerve  cir- 
cuit, which  terminates  in  some  effector.  These  circuits  are 
called  nervous  arcs. 

The  connection  of  successive  neurons  in  the  nervous  arc  is 
not  a  complete  soldering  of  the  ends  together.  It  jsj,  peculiar 
sort  of  connectiop, 
not  fullyunder  stood. 
The  minute  branch- 
ing  fibrils  at  the  far 
end  of  one  neuron 
are  meshed  in  with 
the  fibrils  at  the  near 
end  of  the  next  neu- 
ron, like  the  branches 
of  two  bushes  close 
together  in  a  clump. 
At  these  intermesh- 
ing  points  the  nerve 
impulse  passes  across 
from  one  neuron  to 
the  next,  just  as  in  a 
copper  wire  of  many 
strands  the  electric 
current  passes  over 
to  another  piece 
of  wire  when  the 
strands  of  the  two  are  meshed  together 


Pig.  6.  —  Various  Types  of  Stnapses 

S= synaptic  regions,  where  two  neurons  mesh  together. 
(From  Thomdike,  after  Van  Gehuchten.] 


The  junction  point 
of  two  successive  neurons  is  called  a  synapse.    [Fig.  6.] 

^  The  side  connections  by  means  of  the  collaterals  should  not  be  forgotten. 
They  correspond  to  the  branching  of  an  electric  lighting  system. 


«4    STRUCTURE  OF  THE  NERVOUS  SYSTEM  [ch.  n 


The  synapse  does  not  transmit  nerve  impulses  as  readily  as 
the  nerve  fiber;  it  oflFers  more  or  less  resistance  to  the  passage. 
Sometimes  the  resistance  at  a  synapse  is  so  great  that  the 

impulse  is  unable  to  pass  over  at 
all  into  the  next  neuron.  In  such 
cases  the  pathway  is  blocked,  and 
either  (1)  the  impulse  goes  no  fur- 
ther, or  (2)  it  passes  into  some  col- 
lateral and  through  the  synapse  at 
its  end  into  a  neuron  belonging  to 
a  different  circuit.  The  synapses 
and  the  resistance  which  they  offer 
to  the  transmission  of  nerve  im- 
pulses are  very  important  factors  in 
determining  what  pathway  a  given 
nerve  impulse  will  take.  Our  abil- 
ity to  learn  new  actions  depends  on 
the  shunting  of  nerve  impulses  into 
new  paths  by  means  of  collateral 
synapses. 

General  Plan  of  the  Nervous 
System. — The  neurons  are  not  scat- 
tered through  the  body  promiscu- 
ously. They  form  great  masses  in 
the  head,  constituting  the  brain; 
elsewhere  in  the  body  a  number 
of   neurons  run  close  together  in 

Fig.  7.  —  Brain  and  Cord  in  Position 

In  the  head  is  the  brain,  consisting  of  the  cerebrum 
and  beneath  it  the  cerebellum  (CBL)  and  medulla 
(MED).  The  spinal  cord  is  the  long  white  line  extend- 
ing down  from  the  medulla.  The  peripheral  nerves 
branch  off  from  the  cord  at  intervals  ;  their  beginnings 
are  shown  projecting  down  toward  the  right  in  the 
drawing.  C  I  to  C  VIII  =  cervical  nerves;  TH  I  to 
TH  XII  =  thoracic;  L  I  to  L  V  =•  lumbar;  S  I  to  S  V 
=  sacral;  COC  I  =  coccygeal. 


CH.  II 


GENERAL  PLAN 


I  cE&ncAi  mars 


KOJUCIC  MSSVB 


OAHeujLTa  cou 


-■luauiaan 


coccrosAL  fitvs 


mVM  TUMMxtS 


Pig.  8.  —  Central  Portion  of  Nervous  System 

Viewed  from  the  front.  The  brain  extends  down  to  'I  cervical  nerve';  below  this  is  the 
spinal  cord  with  beginnings  of  the  peripheral  nerves  as  they  leave  the  cord  (numbered  at  right). 
To  left  (very  black)  are  shown  the  sympathetic  ganglia  of  the  autonomic  system:  the  corre* 
spending  ganglia  to  right  of  cord  are  not  shown.  [From  Herrick,  after  Allen  Thompson  and 
Rauber.) 


26    STRUCTURE  OF  THE  NERVOUS  SYSTEM  [cH.n 

bundles.  The  nerves  which  are  visible  to  the  naked  eye 
are  bundles  of  neurons  lying  side  by  side.  The  individual 
neurons  in  any  such  bundle  or  nerve  are  insulated  from  one 
another.  The  nerve  impulse  does  not  jump  across  from  one 
neuron  to  those  beside  it,  but  passes  along  the  same  fiber  to 
the  synapse  at  the  end,  and  over  into  another  neuron  which 
is  the  extension  of  the  same  path. 

The  main  nervous  system'  consists  of  the  brain,  spinal  cord, 
and  peripheral  nerves.  [Figs.  7,  8.]  There  is  also  a  somewhat 
independent  system  of  nerves  called  the  sympathetic  or 
autonomic  system,  which  controls  our  digestion,  heart,  and 
other  internal  organs.     [Fig.  8;  cf.  Fig.  15.] 

Peripheral  Nerves.  —  The  peripheral  nerves  are  the  path- 
ways which  connect  the  centers  in  the  brain  or  spinal  cord 
with  the  receptors  or  effectors.  They  are  of  two  sorts: 
sensory  and  motor.  The  sensory  nerves  connect  the  receptors 
with  the  cord  or  with  the  brain;  they  carry  nerve  impulses 
inward  from  some  receiving  organ  to  some  ceuteg.  The 
motor  nerves  connect  the  cord  or  brain  with  the  muscles  and 
ot^er  effector  organs  throughout  the  body.  They  carry  nerve 
impulses  out  from  some  center  to  some  ^ffectoy .^  Tfie  sen- 
sory and  motor  nerves  which  connect  with  parts  of  the  body 
below  the  head  pass  into  the  cord  on  their  way  to  or  from  the 
brain;  they  are  called  spinal  nerves.  There  are  also  sensory 
and  motor  nerves  in  the  head  which  enter  the  brain  directly, 
without  passing  through  the  cord;  these  are  called  cranial 
nerves.  For  instance,  the  olfactory  nerve  is  a  sensory  cranial 
nerve  leading  from  the  smell  receptors  in  the  nostrils  to  the 
center  for  smell  in  the  brain.  There  are  also  motor  nerves 
leading  from  the  brain  to  the  face  muscles  which  are  used  in 
smiling;  they  do  not  pass  through  the  spinal  cord. 

Spinal  Cord.  —  The  spinal  cord  runs  up  the  back  from  the 

^  Called  the  cerebrospinal  system. 

*  There  are  also  mixed  peripheral  nerves,  which  contain  both  sensory  and 
motor  neurons,  grouped  into  separate  bundles,  but  running  side  by  side. 


-TH.  n] 


SPINAL  CORD 


27 


lower  extremity  of  the  trunk  to  the  head,  where  it  enters  the 
brain.  Roughly  speaking  it  is  about  as  thick  as  your  little 
finger.  It  lies  inside  the  backbone.  The  separate  segments 
(vertebrae)  which  make  up 
the  backbone  are  hollow, 
and  the  cord  lies  within  this 
hollow  tube.  The  nerves 
enter  or  leave  the  cord  in  the 
space  between  each  pair  of 
vertebrae.  [Fig.  7.]  At  each 
vertebral  juncture  two  sen- 
sory nerves  enter  the  cord  — 
one  from  the  right,  one  from 
the  left  —  and  two  motor 
nerves  go  out.  [Fig.  8.]  The 
sensory  and  motor  nerves  on 
the  left  side  join  together 
just  outside  the  cord  [Fig.  9] 
and  run  as  a  single  nerve  to 
the  region  of  the  body  where 
they  terminate;  there  the 
nerve  breaks  up  and  each 
neuron  proceeds  separately 
to  its  final  destination.  The 
corresponding  sensory  and 
motor  nerves  on  the  right 
side  proceed  in  a  similar  way. 
Both  of  the  sensory  nerves 
(right  and  left)  enter  the 
cord  from  the  dorsal  direc- 
tion—  that  is,  at  the  back; 
while  the  motor  nerves  pass 
out  in  the  ventral  direction  — 
body. 

If  we  cut  through  the  cord  horizontally,  it  is  seen  as  a  mass 


Fig.  9.  —  Cross-Section  of  Cord 

The  central  gray  matter  (G)  is  shaped  like 
an  H,  and  is  surrounded  by  white  matter  (W). 
From  the  ventral  or  front  horn  (VH)  of  gray 
matter  emerges  the  motor  root  (MR)  of  a 
spinal  nerve  (SP);  the  sensory  root  (SR)  of 
the  same  nerve  enters  the  dorsal  or  back  horn 
(DH),  which  is  more  pointed  than  the  ventral. 
Near  the  junction  of  the  two  roots  is  the  spinal 
ganglion  (SG)  consisting  of  sensory  cell-bodies. 

The  nerve  shown  in  the  figure  is  on  the  left 
side  of  the  body;  the  roots  of  the  correspond- 
ing right-side  nerve  join  the  cord  at  the  farther 
pair  of  boms.     [Modified  from  Testut.] 

that  is,  toward  the  front  of  the 


28    STRUCTURE  OF  THE  NERVOUS  SYSTEM  [cH.n 

of  whitish  substance,  surrounding  a  grayish  mass  which  looks 
somewhat  like  the  letter  H.  [Fig.  9.]  The  gray  matter  is 
composed  largely  of  cell-bodies  with  the  fibers  leading  into 
them.  The  white  matter  is  composed  of  axon  fibers  with  no 
cell-bodies.  The  difference  in  coloring  is  due  to  the  grayish 
tinge  of  the  cell-bodies. 

The  peripheral  sensory  and  motor  nerves  from  all  over  the 
body  below  the  head  pass  into  the  gray  matter  of  the  cord 
and  terminate  there.  At  their  terminus  in  the  cord  they  con- 
nect with  two  distinct  paths:  (1)  There  are  reflex  connecting 
neurons  in  the  gray  matter  which  join  the  ends  of  the  sensory 
neurons  directly  with  the  ends  of  the  motor  neurons  in  the 
cord,  so  that  a  nerve  impulse  may  come  into  the  cord  and  pass 
out  immediately,  without  going  up  to  the  brain.  This  direct 
connection  is  what  causes  the  knee-jerk  and  other  spinal 
reflexes.  (2)  There  are  also  secondary  sensory  neurons  con- 
nected with  the  ends  of  each  sensory  neuron  in  the  gray 
matter  of  the  cord  which  lead  up  to  the  brain,  and  corre- 
sponding secondary  motor  neurons  which  descend  from  the 
brain  and  connect  with  the  peripheral  motor  neurons  in  the 
cord.  These  indirect  connections  are  used  in  voluntary 
movements.  The  white  matter  of  the  cord  is  made  up  of 
these  conducting  fibers  which  connect  the  brain  with  the 
peripheral  sensory  and  motor  neurons. 

The  H  shape  ^  of  the  gray  matter  in  the  cord  is  due  to  these 
connections:  (1)  The  direct  reflex  connections  between  the 
sensory  and  motor  fibers  form  the  two  uprights  of  the  H;  and 
(2)  the  sensory  fibers  (with  gray  cell-bodies),  crossing  over 
from  right  to  left  before  they  pass  up  toward  the  brain,  make 
the  cross-bar. 

The  thickness  of  the  cord  varies.     It  is  thickest  near  the 

head  and  tapers  down  at  the  lower  end.     This  is  because  a 

pair  of  nerves  pass  out  at  each  of  the  vertebral  openings, 

reducing  the  size  of  the  cord  as  we  proceed  downward.    The 

^  Turn  Fig.  9  left  side  up  and  you  see  the  H  clearly. 


Fig.  10.  —  Base  of  Brain 

Brain  viewed  from  below,  looking  upwards.  Front  of  head  is  at  top  of  the  drawing,  back 
of  head  is  at  bottom.  In  the  drawing  the  pons,  medulla,  and  cerebellum  are  supposed  to  be 
nearer  you  than  the  cerebrum.  Basal  ganglia  lie  in  center  of  picture.  Lobes  of  cerebrum 
(lobus)  are  underscored.  Small  folds  of  the  lobes,  called  convolutions  (gyrus),  are  named 
(right  side).  Cranial  nerves  are  named  (right)  and  numbered  (left).  Beginning  of 
•pinal  cord  (medulla  spinalis)  is  shown  below.     [From  Strilmpell  asd  Jakob.) 


CH.  Ill  SPINAL  CORD  29 

decrease  is  not  uniform;  there  are  two  distinct  bulges:  one 
where  the  great  nerves  of  the  arms  leave  the  cord,  the  second 
where  the  nerves  pass  out  to  the  legs. 

The  spinal  nerves  are  named  according  to  the  region  of  the 
body  which  they  serve,  and  within  each  region  they  are  num- 
bered from  the  top  downward.  There  are  in  all  thirty-one 
pairs  of  spinal  nerves.   [Fig.  8.] 

The  sensory  nerves  which  enter  the  cord  from  the  right  side 
connect  with  neurons  that  cross  over  and  pass  up  on  the  left 
side,  and  vice  versa;  in  every  case  the  sensory  paths  in  the 
cord  are  on  the  opposite  side  from  that  on  which  they  enter. 
The  motor  fibers  generally  cross  at  the  upper  end  of  the  cord, 
so  that  the  motor  paths  in  the  cord  are  on  the  same  side  as  the 
peripheral  motor  nerves  with  which  they  connect.  But  in 
every  case  the  sensory  and  motor  nerves  which  serve  the  right 
side  of  the  body  connect  with  the  left  side  of  the  brain,  and 
vice  versa.  In  other  words,  the  left  side  of  the  brain  receives 
impulses  from  the  right  side  of  the  body  and  controls  move- 
ments on  that  side,  while  the  right  side  of  the  brain  is  con- 
nected with  the  left  side  of  the  body. 

The  Brain.  —  The  human  brain  is  a  very  intricate  affair.^ 
It  consists  of  the  medulla  oblongata,  cerebellum,  pons  Varoliit 
and  cerebrum  or  great  brain;  the  cerebrum  is  divided  into  the 
basal  ganglia  and  the  cortex  or  covering.^  In  addition  there 
are  twelve  pairs  of  cranial  nerves,  which  connect  with  re- 
ceptors and  effectors  in  the  head.     [Fig.  10.] 

Of  the  twelve  cranial  nerves,  some  are  sensory,  some  motor, 
and  some  contain  both  sensory  and  motor  branches.  Sen- 
sory nerves  or  branches  connect  with  the  eye,  ear,  and  organs 
of  taste  and  smell,  and  with  receptors  for  the  sense  of  touch 
in  the  lining  of  the  mouth  and  nose,  and  in  the  skin  of  the  face. 

'  See  Frontispiece.  If  possible  a  brain  model  or  specimen  should  be 
examined. 

*  The  term  brain-slem  is  used  to  designate  all  the  brain  except  the  cerebel- 
lum and  the  cortex  with  its  connecting  tracts. 


so    STRUCTURE  OF  THE  NERVOUS  SYSTEM  [ch.ii 

It  is  through  these  nerves  that  we  get  sensations  of  sight, 
hearing,  and  the  other  special  senses,  as  well  as  touch  sensa- 
tions from  the  skin  of  the  head.  Motor  nerves  lead  to  the 
various  muscles  in  the  head,  including  the  eye  muscles  and 
those  of  the  lips,  tongue,  jaws,  and  throat  which  are  used  in 
eating  and  speaking.  The  cranial  nerves  and  receptors  will 
be  examined  in  more  detail  in  connection  with  sensation 
(chs.  iv,  v). 

The  medulla  is  really  a  continuation  of  the  spinal  cord,  but 
is  much  thicker.  It  is  the  region  where  the  motor  fibers  cross, 
and  it  is  also  the  assembling  point  for  fibers  connecting  the 
cord  with  the  various  parts  of  the  brain  beyond. 

The  cerebellum  is  a  spherical  mass  of  nervous  matter  which 
lies  at  the  back  of  the  medulla  and  somewhat  above  it.  It 
contains  centers  for  coordinating  our  movemgpts;  by  means 
of  its  activity  we  are  able  to  maintain  our  equilibrium  and  to 
make  other  simple  motor  adjustments  without  special  at- 
tention. 

The  pons  is  a  broad  band  of  nerve  fibers  lying  in  front  of 
the  medulla  and  crossing  it  horizontally.  It  is  situated  some- 
what above  the  cerebellum. 

Immediately  above  the  parts  just  mentioned  is  the  cere- 
brum or  great  brain.  Its  interior  consists  of  a  number  of 
odd-shaped  masses  of  nervous  matter  called  the  basal  ganglia, 
which  serve  various  purposes  in  the  reception  and  treatment 
of  nerve  impulses.  Some  of  these  masses  connect  with  the 
cranial  nerves;  others  are  intermediate  stations  between  the 
cord  and  cortex.  It  would  require  an  undue  amount  of  time 
to  describe  their  relative  position  and  uses,  and  this  can  only 
be  done  satisfactorily  in  connection  with  an  examination  of  a 
brain  model  or  actual  dissection.  For  our  purpose  the  most 
important  basal  ganglia  are  the  two  optic  thalami,^  right  and 

^  This  name  was  adopted  because  the  thalami  were  found  to  lie  at  the  end 
of  the  optic  nerves.  Later  they  were  found  to  be  the  terminals  of  other 
sensory  nerves  also;  the  olfactory  nerve  is  apparently  not  connected  with 


Fig.  12.  —  Cortex  from  Above 

Showing  the  hemispheres,  separated  by  the  medial  Bssure.  Front  of  head  is  at  top  of 
the  drawing.  FL  =  frontal  lobe;  ACC  =  anterior  central  convolution;  RF=  Rolandic  (or 
central)  fissure;  PCC  =  posterior  central  convolution;  PL  =  parietal  lobe;  OL  =  occipi- 
tal lobe. 


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CH.  ii]  THE  BRAIN  31 

left,  which  contain  the  'primary  centers  for  stimuli  from  all 
the  receptors.     [Fig.  11.] 

The  Cortex.  —  The  cortex  is  a  thin  sheet  of  gray  nervous 
matter  which  lies  above  and  around  the  basal  ganglia,  almost 
completely  surrounding  them.'  The  cortex  and  underlying 
portion  of  the  cerebrum  is  divided  by  a  deep  medial  fissure 
into  two  parts,  called  the  right  and  left  hemispheres,  which 
are  connected  beneath  by  a  mass  of  white  fibers  called  the 
corpus  callosum. 

The  surface  of  the  cortex  is  covered  with  rounded  creases, 
which  give  it  the  appearance  of  being  wrinkled  or  folded. 
[Fig.  12.]  Two  deep  creases  on  each  side  divide  the  cortex 
into  readily  distinguishable  parts.  They  are  called  the  fissure 
of  Sylvius  and  central  fissure  or  fissure  of  Rolando.  [Fig.  13.] 
For  convenience  in  reference,  the  regions  marked  off  by  these 
and  the  medial  fissure  are  called  lobes  and  are  given  separate 
names,  though  their  functions  are  not  always  distinct.  In 
each  hemisphere  there  are  four  lobes;  the  frontal,  temporal, 
parietal,  and  occipital. 

The  surface  of  the  cortex  is  gray,  covering  a  mass  of  white 
matter  beneath  .^  This  means  that  the  cortex  is  made  up 
largely  of  cell-bodies,  while  the  part  beneath  consists  of  fibers 
leading  to  or  from  the  cortex.  The  thin  cortex  is  the  final 
goal  of  the  sensory  fibers  and  incoming  nerve  impulses  and  it 
is  the  starting-point  of  the  most  highly  organized  motor  im- 
pulses. The  cortex  is  the  great  central  control  station  of  the 
nervous  system. 

There  is  no  single  dominating  center  in  the  cortex,  where 
all  incoming  impulses  gather  and  from  which  all  motor  im- 
pulses are  generated.  On  the  contrary,  the  cortex  contains 
many  separate  receiving  centers  and  many  separate  motor 

thalatni.  In  the  illustrations  of  the  brain  the  Latin  names  are  used;  the 
English  equivalent  is  obvious  in  every  case. 

^  The  name  cortex  means  bark  or  rind. 

'  Note  that  this  arrangement  is  the  reverse  of  the  cord,  where  the  gray 
matter  lies  inside  the  white. 


82    STRUCTURE  OF  THE  NERVOUS  SYSTEM  [ch.  ii 

centers.  [Fig.  14.]  The  higher  or  control  centers  for  sight 
(vision)  and  hearing  Ue  in  widely  separated  regions  of  the 
cortex.  They  connect  with  the  lower  or  primary  centers  for 
these  senses,  which  are  situated  in  the  optic  thalami  beneath. 
Near  the  cortical  hearing  center  is  a  special  center  for  audi- 


Fig.  14.  —  Centers  in  the  Cortex 

Same  view  a«  Fig.  13.  Diagram  showing  the  touch  and  motor  centers  from  toes  to  lips,  and 
relation  of  language  (speech)  centers  to  centers  for  sight  (vision),  hearing,  tongue,  and  lips. 
[From  Uerrick,  after  Starr.) 

tory  language  —  that  is,  for  hearing  and  understanding 
spoken  words.  There  are  also  special  cortical  centers  for 
speaking,  writing,  and  reading. 

The  arrangement  of  the  cortical  centers  for  touch  and  for 
moving  various  parts  of  the  body  is  rather  striking,  [Fig.  14.] 
They  lie  along  the  fissure  of  Rolando,  and  are  arranged  in 
much  the  same  order  as  the  parts  of  the  body  which  they 
serve:  first,  at  the  top,  the  centers  for  the  toes,  then  for  the 
foot,  leg,  thigh,  and  so  on  to  the  centers  for  cheek,  jaws,  lips. 
Notice  that  the  order  is  inverted:  the  center^  for  the  very 
lowest  part  of  the  body  —  the  toes  —  are  highest  up  in  the 
cortex.     The  motor  centers  in  this  group  lie  on  the  front  wall 


CH.  ii]  THE  CORTEX  38 

of  the  Rolandic  fissure;  and  just  opposite  each  one,  on  the  rear 
or  posterior  wall,  lies  the  corresponding  sensory  (touch)  center. 
In  Fig.  14  the  center  for  touch  sensations  from  the  toes  lies 
just  to  the  right  of  the  center  for  moving  the  toes,  and  so  on. 

The  cortical  centers  for  sensory  and  motor  functions  which 
we  have  described  are  called  'projectiorj,  r^ynft^fff^  |->pngiigf>  the 
impulses  are  projected  up  from  the  primary  sensory  centers 
(and  down  to  the  primary  motor  centers)  in  the  basal  ganglia 
beneath.  They  are  concerned  not  so  much  with  the  recepn 
tion  of  sensory  impulses  as  with  combining  and  elaborating 
them.  To  take  one  example:  the  primary  center  for  sight  is 
in  the  thalami.  A  person  gets  visual  impressions  and  is  able 
to  avoid  obstacles  in  walking  if  the  optic  nerves  leading  from 
eyes  to  the  thalami  are  intact,  even  though  the  visual  center 
in  the  cortex  is  destroyed;  but  he  cannot  recognize  objects 
without  the  cortical  center  for  sight;  and  he  cannot  read  if  the 
word-seeing  center  is  destroyed,  though  he  can  see  the  letters 
on  the  page  as  black  marks. 

Besides  the  projection  areas,  the  cortex  contains  masses  of 
connecting  neurons.  The  regions  in  which  they  are  located 
are  called  association  areas.  The  association  areas  are  filled 
with  bundles  of  nerve  fibers  which  form  connections  between 
the  various  projection  areas.  When  you  touch  and  see  and 
smell  a  flower,  all  at  the  same  time,  the  association  fibers 
connecting  the  cortical  centers  for  touch,  sight,  and  smell  are 
brought  into  play,  so  that  these  three  impressions  combine 
into  the  perception  of  a  single  object  —  the  flower.  In  read- 
ing aloud  the  association  fibers  joining  the  word-seeing  and 
word-uttering  centers  are  used  to  connect  the  cortical  proc- 
ess of  understanding  words  with  the  cortical  process  of 
speaking.  The  cortical  centers  in  one  hemisphere  are  con- 
nected with  the  corresponding  centers  in  the  other  by  com- 
missure fibers  passing  through  the  callosum. 

In  general  there  are  corresponding  centers  for  each  sensory 
and  each  motor  function  in  the  two  hemispheres.    The  corti- 


34    STRUCTURE  OF  THE  NERVOUS  SYSTEM  [ch.  ii 

cal  centers  for  the  right  half  of  the  body  are  in  the  left  hemi- 
sphere, and  vice  versa.  The  visual  centers  form  an  apparent 
exception.  The  fibers  from  the  left  half  of  both  eyes  run  to 
the  left  thalamus,  and  those  from  the  right  half  to  the  right 
thalamus,  half  of  each  optic  nerve  crossing  over  at  a  place 
called  the  optic  chiasm.  But  since  the  visual  picture  is  re- 
versed on  the  retina,  the  right  half  of  each  eye  sees  objects 
situated  to  your  left,  and  vice  versa,  so  that  even  here  the  law 
holds. 

The  four  language  centers  (for  speaking,  writing,  hearing 
words,  and  reading)  are  found  in  only  one  hemisphere  —  not 
in  both.  In  right-handed  persons  the  language  centers  are 
all  in  the  left  hemisphere  of  the  brain.  This  is  proved  by 
cases  of  brain  disease.  If  certain  areas  of  the  cortex  are 
destroyed  or  injured,  there  is  a  language  disturbance,  pro- 
vided the  injury  is  in  the  left  hemisphere;  if  the  corresponding 
region  in  the  right  hemisphere  is  destroyed,  there  is  no 
language  disturbance,  showing  that  there  is  no  language  area 
on  this  side. 

Autonomic  System.  —  The  operation  of  the  digestive 
organs,  heart,  lungs,  and  other  internal  organs  is  regulated 
by  a  system  of  nerves  which  do  not  form  part  of  the  main 
(or  cerebrospinal)  system.  This  is  called  the  autonomic 
system.  [Fig.  15.]  It  consists  of  a  number  of  more  or  less 
independent  groups  of  nerves,  each  of  which  has  a  small 
central  mass  of  its  own,  called  a  ganglion.  There  are  im- 
portant nerve  groups  (called  plexuses)  belonging  to  this  sys- 
tem in  various  parts  of  the  body :  at  the  base  of  the  heart,  in 
the  upper  abdominal  cavity,  and  in  the  lumbar  region.  They 
control  the  circulation,  digestion,  and  reproductive  organs. 
There  are  also  smaller  ganglia  in  the  head.  Two  series  of 
ganglia  are  situated  near  the  spinal  cord,  one  on  each  side  of 
the  body.  [Fig.  15;  cf.  Fig.  8.]  Each  of  these  ganglia  con- 
nects with  the  next  higher  and  lower  ganglia,  and  with  the 
neighboring  spinal  nerve. 


CH.  II  ] 


AUTONOMIC  SYSTEM 


35 


Superior    cervical    ganglion 
of    sytnpathellc  ' 


PharyngeeJ    plexus 

Middle  cervical    ganglion 

o^    sympathetic 
Inferior  cervical    ganglion 
of   sympathati? 


yThoracic 
plexuses 


Abdominal 
plexuses 


Pelvic 
plexuses 


Fig.  15.  —  Autonomic  Nervous  System 

Sympathetic  ganglia  and  plexuses  are  shown  in  heavy  black;  numbering  of  autonomic  gang- 
lia  corresponds  to  that  of  neighboring  spinal  nerves;  C  I  =  first  cervical,  T  I  °>  first  thoracic, 
L  I  =  first  lumbar,  etc.    Compare  Fig.  8.    [From  Lickley,  after  Schwalbe.] 


36  STRUCTURE  OF  THE  NERVOUS  SYSTEM  [ch.  ii 

The  activity  of  the  autonomic  system  governs  the  or- 
ganic or  biological  life  processes,  so  that  usually  these  operate 
without  conscious  control.  But  the  connection  between  the 
autonomic  gangUa  and  the  main  nervous  system  makes 
possible  an  interplay  between  our  organic  and  higher  mental 
processes.  By  means  of  this  connection,  for  instance,  we  are 
able  to  regulate  our  breathing,  although  breathing  ordinarily 
goes  on  independent  of  brain  supervision,  by  means  of  the 
autonomic  system.  In  the  same  way  our  worries  sometimes 
affect  our  digestion,  through  motor  impulses  from  the  brain 
which  pass  over  into  the  autonomic  digestive  nerves.  On  the 
other  hand,  chronic  indigestion  often  affects  our  temper  or 
makes  us  depressed.  In  this  case  the  autonomic  system  acts 
indirectly  upon  the  cerebrospinal  system :  the  digestive  trouble 
causes  toxic  chemical  products,  which  stimulate  the  organic 
senses  and  give  rise  to  unpleasant  sensations. 

Summary.  —  The  nervous  system  is  composed  of  many 
millions  of  special  cells  called  neurons.  The  distinctive 
features  of  the  neuron  are  its  long  white  axon  fiber  projecting 
from  the  gray  cell-body,  its  collateral  branches,  its  dendrites, 
and  the  minute  fibrils  in  which  all  these  terminate.  Neu- 
rons connect  together,  end  to  end,  by  the  intermeshing  of 
this  fibrillar  network;  the  connection  is  called  a  synapse. 

The  nervous  system  is  divided  into  the  main  (or  cere- 
brospinal) and  the  autonomic  system.  The  autonomic  sys- 
tem is  concerned  chiefly  with  the  bodily  life  processes  — 
digestion,  circulation,  etc.  It  connects  with  the  main  system, 
however,  so  that  our  mental  and  bodily  life  processes  influ- 
ence each  other. 

The  cerebrospinal  nervous  system  consists  of  the  brain, 
cord,  and  peripheral  nerves.  The  sensory  peripheral  nerves 
lead  inward  from  the  receptors;  the  motor  nerves  lead  out- 
ward to  glands  or  muscles.  The  sensory  nerves  always  carry 
impulses  in  from  a  receptor  toward  a  center  —  never  in  the 
other  direction.     The  motor  nerves  always  carry  impulses 


CH.  n]  SUMMARY  87 

out  from  the  center  toward  the  effector.  Some  peripheral 
nerves  connect  the  end  organs  with  the  cord  and  lead  to  the 
brain  through  pathways  within  the  cord;  the  cranial  nerves 
in  the  head  connect  directly  with  the  brain  without  passing 
through  the  cord. 

The  cord  contains  both  conducting  nerves  and  centers. 
The  gray  matter  within  the  cord  consists  of  cells  which  serve 
as  centers  for  the  immediate  connection  of  incoming  and 
outgoing  nerves.  These  spinal  centers  cause  quick,  uncon- 
scious movements  called  reflexes.  The  knee-jerk  is  a  spinal 
reflex.  The  white  matter  of  the  cord  surrounds  the  gray 
matter;  it  consists  of  masses  of  sensory  fibers  which  continue 
the  sensory  paths  on  toward  the  brain,  and  motor  fibers  con- 
necting the  brain  with  the  peripheral  motor  nerves. 

The  brain  comprises  all  higher  nerve  centers,  where  sensory 
nerves  connect  with  other  sensory  nerves,  motor  with  other 
motor  nerves,  and  sensory  with  motor  nerves.  The  cere- 
bellum lies  at  the  base  of  the  brain,  and  contains  a  system  of 
centers  for  regulating  our  equilibrium  and  general  posture. 
Above  this  Ues  the  cerebrum,  or  great  brain,  consisting  of  basal 
ganglia  and  cortex.  The  basal  ganglia  contain  the  lower 
control  centers  for  receiving  impulses  from  the  receptors. 

Surrounding  the  basal  ganglia  is  the  cortex,  divided  into  two 
hemispheres,  which  acts  as  the  highest  controlling  station  of 
the  system.  In  it  are  the  projection  centers  for  incoming  and 
outgoing  impulses,  and  association  areas  for  connecting  these 
together.  The  cortex  contains  many  million  neurons.  Our 
highest  intelligent  activities,  such  as  perception,  language, 
thought,  and  voluntary  movements,  depend  on  the  intricate 
connections  of  neurons  in  the  cortex. 

Practical  Exercises: 

6.  Report  any  instances  of  indigestion  or  other  bodily  disturbance  due  to 
anxiety  or  disappointment. 

7.  Describe  any  brightening  of  your  outlook  on  the  world  due  to  improve- 
ment of  your  bodily  condition;  or  depression  caused  by  bodily  ailment. 

8.  Test  the  involuntary  eye-wink  of  some  friend  by  an  unexpected  loud 


38    STRUCTURE  OF  THE  NERVOUS  SYSTEM  [ch.  n 

noise  or  quick  movement  past  the  eye;  note  the  voluntary  resistance 
to  the  wink  when  the  experiment  is  repeated  several  times.  Report  the 
experiment,  including  his  description  of  the  experience.  Test  the  iris 
reflex  with  a  flash-light  in  a  dark-room. 
9.  Describe  (or  name)  the  different  sorts  of  muscular  movement  which 
you  can  observe  in  your  face  and  head. 
10.  Make  a  sketch  of  the  cortex  of  the  left  hemisphere,  indicating  the 
various  centers. 

[Exercises  6  and  7  are  on  the  relation  between  the  cerebrospinal  and 
automatic  systems;  8  is  on  the  reflex  nerve  paths;  9  is  on  the  motor- 
nerve  terminals;  10  is  on  the  topography  of  the  brain.] 

References: 

On  cells  in  general:  E.  B.  Wilson,  The  Cell. 

On  the  nervous  system:  J.  D.  Lickley,  The  Nervous  System;  C.  J.  Herrick, 
Introduction  to  Neurology;  K.  Dunlap,  Outline  of  Psychobiohgy. 

On  the  cortex  and  its  centers:  Ladd  and  Wood  worth.  Elements  of  Physio- 
logical Psychology,  Part  I,  chs.  9, 10. 


CHAPTER  m 
OPERATION  OF  THE  NERVOUS  SYSTEM 

How  the  Nervous  System  Works.  —  Despite  the  complex- 
ity of  the  nervous  system,  its  general  manner  of  operation 
is  simple:  (1)  Some  one  of  the  receptors  is  stimulated.  (2) 
The  stimulus  starts  a  nerve  impulse  in  the  sensory  neuron 
connected  with  this  receptor,  and  this  impulse  travels  along  a 
sensory  path  to  a  center  in  the  cord  or  brain.  (3)  Impulses 
which  reach  the  sensory  centers  at  the  same  time  are  col- 
lected and  combined  with  the  traces  left  by  previous  impulses 
and  proceed  to  a  motor  center.  (4)  A  motor  impulse  goes  out 
from  the  motor  center  along  some  motor  nerve  to  a  muscle  or 
gland.  (5)  The  muscle  contracts  and  a  bodily  movement 
occurs,  or  if  a  gland  is  affected,  secretion  results. 

This  entire  circuit  is  called  a  nervous  arc.  Nerve  energy 
always  passes  through  a  nervous  arc,  and  always  in  the  same 
order.  A  concrete  example  is  the  way  the  nervous  system 
operates  when  a  man  tries  to  catch  a  baseball.'  (1)  The  light 
waves  from  the  ball  reach  the  player's  eye  and  stimulate  it. 
(2)  The  optic  nerve  carries  the  effect  to  the  visual  center  in 
his  brain.  (3)  In  the  brain  the  impressions  from  all  parts  of 
the  ball  and  the  background  around  it  are  put  together.  The 
resulting  picture  is  combined  with  other  impressions  received 
at  the  same  time  and  with  the  player's  memories;  then  a  nerve 
impulse  goes  to  the  brain  centers  for  arm  and  hand  move- 
ment. (4)  The  motor  nerves  thereupon  carry  nerve  impulses 
down  from  the  brain  through  the  cord  and  out  to  the  muscles 
of  the  arm  and  hand.  (5)  When  the  impulse  reaches  these 
muscles  it  causes  them  to  contract.  The  ball  is  caught  if  the 
motor  impulses  are  well  coordinated.  If  the  brain  coordina- 
1  See  Fig.  2,  p.  4. 


40  OPERATION  OF  THE  NERVOUS  SYSTEM  [ch.  m 

tion  is  poor,  the  muscles  do  not  contract  just  right  and  the 
player  misses  or  fumbles  the  ball. 

In  some  cases  the  process  is  simpler  and  in  others  much 
more  complicated  than  this.  Winking  is  the  result  of  a  very 
simple  nervous  operation.  When  an  object  passes  close  to 
your  eye,  the  eye  is  stimulated  very  suddenly.  The  sensory 
nerve  impulse  in  the  optic  nerve  goes  only  to  the  lower  visual 
center.  No  time  is  lost  in  collecting  or  distributing:  the  im- 
pulse passes  directly  over  to  the  center  for  lowering  the  eye- 
lid; the  motor  impulse  goes  out  to  the  eyelid  muscle  at  once, 
and  you  wink.  These  very  simplest  nervous  activities  are 
called  reflexes.  Winking  is  a  cranial  reflex;  its  arc  Kes  within 
the  head. 

There  are  other  simple  arcs  which  do  not  enter  the  head  at 
all;  they  are  called  spinal  reflexes.  [Fig.  16.]  When  some- 
thing unexpectedly  touches  the  skin  of  yom*  hand,  a  sensory 
impulse  is  carried  by  the  sensory  nerve  to  the  cord.  There  it 
passes  over  from  the  dorsal  to  the  ventral  part  of  the  gray 
matter  (on  the  same  side  of  the  body),  and  passes  out  along 
the  motor  nerve  to  the  muscle  in  your  arm;  the  muscle  con- 
tracts, and  you  jerk  your  hand  away. 

Many  human  actions  are  very  complicated  and  involve  an 
intricate  nervous  arc.  Suppose  you  are  going  to  answer  a 
letter.  A  large  number  of  stimuli  affect  you  as  you  read  the 
message.  When  they  reach  the  brain  you  do  not  start  to 
write  at  once,  but  you  think  it  over;  that  is,  there  is  a  period  in 
which  nerve  impulses  are  traveling  from  center  to  center  in 
the  brain,  arousing  memory  pictures  and  thoughts.  After  a 
time  your  thoughts  are  satisfactorily  marshaled,  and  it  is 
then  that  the  motor  impulses  from  the  writing  center  begin 
to  flow  out  to  the  muscles  of  your  fingers  and  wrist. 

In  every  case,  whether  simple  or  complicated,  the  nervous 
activity  consists  of  a  succession  of  five  steps:  (1)  Stimulation 
of  a  receptor;  (2)  condiiction  of  nerve  impulses  toward  a 
center;  (3)  adjustment  of  impulses  at  the  center  or  centers; 


CH.  Ill]  THE  NERVOUS  ARC  41 

(4)  conduction  of  motor  impulses  to  an  effector;  and  (5) 
response  or  activity  by  the  effector.  Each  of  these  steps  must 
be  examined  before  we  can  understand  the  process  as  a  whole. 
We  may  combine  the  two  conduction  processes  and  discuss 
the  questions  in  the  following  order; 

What  is  stimulation? 

What  is  nervous  conduction,  and  what  are  the  other  characteristics 

of  the  nerve  impulse? 
What  is  response? 
What  hapj)ens  at  the  nerve  centers? 

Stimulation.  —  Stimulation  is  the  effect  produced  on  a 
receptor  by  some  object  or  force  in  our  siuroundings  (environ- 


Husc 
Fig.  16.  —  Nervous  Akc  in  Spinal  Reflex 

Showing  path  of  reflex  nerve  impulse  when  the  skin  of  hand  is 
stimulated.  A  sensory  impulse  traveL«  in  direction  of  arrow  to  the 
cord,  entering  at  the  back  (dorsal  root);  the  impulse  crosses  imme- 
diately to  front  of  gray  matter;  thence  a  motor  impulse  goes  out 
through  the  ventral  root  to  muscle  in  the  arm,  producing  muscular 
contraction.     [Prom  Herrick,  after  Van  Gehuchten.] 

ment)  or  within  our  body.  When  you  touch  a  book  or  an 
apple  before  picking  it  up,  the  surface  of  the  object  presses 
against  your  skin  and  quickly  produces  a  change  in  certain 
receptors  called  touch  corpuscles,  which  lie  scattered  about  in 
the  skin;  that  is,  the  pressure  on  the  skin  stimulates  these 


42  OPERATION  OF  THE  NERVOUS  SYSTEM  [ch.  m. 

corpuscles,  and  the  effect  is  communicated  to  the  endings  of 
sensory  neurons  which  lie  in  close  connection  with  the  touch 
corpuscles.  When  light  waves  from  an  object  stimulate 
your  eye  the  effect  is  communicated  to  the  neurons  of  your 
optic  nerve  in  a  similar  way.  In  the  case  of  touch  the  stimih 
lus  is  a  material  body;  in  the  case  of  sight  the  stimulus  is  a 
force.  The  stimulus  acts  in  a  mechanical  way  on  the  receptor 
in  touch  and  hearing;  in  certain  other  senses,  such  as  sight 
and  taste,  the  stimulus  produces  a  chemical  change  in  the 
receptor. 

The  stimulus  may  act  either  from  inside  or  outside  the 
body.  Hunger  is  caused  by  stimulation  of  the  receptors  in 
the  hning  of  the  stomach  and  alimentary  canal.  Here  the 
stimulus  is  inside  the  body.  The  muscle-sense  stimulus  is 
also  inside  the  body.  When  you  bend  your  arm  the  muscle- 
sense  receptors  are  stimulated  by  the  change  in  muscular 
tension  and  this  starts  the  nerve  impulse  which  gives  you  a 
sensation  of  movement.  In  the  case  of  sight,  hearing,  smell, 
and  touch  the  stimulus  is  outside  the  body,  in  the  surrounding 
world,  and  acts  upon  receptors  situated  at  or  near  the  surface 
of  the  body. 

Nerve  impulses  do  not  start  themselves;  they  do  not  origi- 
nate in  the  neurons.  They  always  depend  on  some  stimulus 
which  works  upon  a  receptor  organ,  such  as  the  eye  or  touch 
corpuscles;  this  effect  is  transmitted  immediately  to  the 
sensory  neurons  whose  endings  are  in  close  connection  with 
these  receptors.  There  is  one  partial  exception  to  this  rule. 
The  nerves  which  give  us  pain  sensations  have  no  receptor 
organs.  Pain  is  caused  by  wear  and  tear  of  the  tissues  of  the 
body;  the  destruction  of  tissue  is  a  stimulus  which  works 
directly  on  the  sensory  nerves  for  pain.  This  means  merely 
that  in  the  case  of  pain  there  is  not  a  double  process  of  stimu- 
lation. In  all  other  cases  the  stimulus  affects  the  receptor 
and  then  the  receptor  affects  the  sensory  nerve. 

The  nature  of  the  impulse  in  the  sensory  nerve  is  deter- 


CH.  ra]  STIMULATION  43 

mined  in  the  first  instance  by  the  nature  of  the  stimulus. 
The  intensity  of  the  impulse  is  determined  by  the  intensity  or 
force  of  the  stimulus.  The  brighter  the  light  which  strikes 
the  eye,  the  more  intense  is  the  resulting  impulse  in  the  optic 
nerve;  the  greater  the  pressure  of  an  object  on  the  skin,  the 
more  intense  is  the  resulting  impulse  in  the  nerve  for  touch. 
The  quality  of  the  stimulus  also  determines  the  impulse  in 
certain  cases.  The  dififerent  light  waves  which  strike  the  eye 
produce  differences  in  the  nerve  impulse,  which  enable  us  to 
distinguish  colors. 

The  sensory  impulse  depends  also  on  the  nature  of  the 
receptor i  and  how  it  is  affected  by  the  stimulus.  A  well-de- 
veloped eye  is  capable  of  distinguishing  more  differences  of 
intensity  and  more  colors  than  an  eye  of  the  primitive  type 
found  in  very  low  animals.  A  human  being  can  tell  more 
readily  than  a  starfish  that  it  is  getting  lighter  or  darker. 
This  is  because  the  human  eye  is  more  perfect;  its  reactions 
to  Ught  are  more  finely  graded.  Consequently  the  human  eye 
passes  on  to  the  optic  nerve  a  greater  variety  of  different 
effects,  and  these  differences  are  transmitted  to  the  brain; 
so  that  man  is  able  to  detect  much  finer  gradations  of  light 
than  the  starfish. 

In  point  of  fact,  the  receptor  has  more  to  do  with  determin- 
ing the  form  of  the  nerve  impulse  than  the  stimulus.  If  two 
coins,  a  cent  and  a  nickel,  be  placed  one  above  the  other  be- 
neath the  tip  of  the  tongue,  so  that  they  touch  the  tongue  and 
each  other,  we  get  a  pecuhar  metalhc  taste  sensation.  Neither 
coin  separately  can  be  tasted.  There  is  no  taste  stimulus 
properly  speaking,  but  chemical  action  (electrolysis)  is  set  up 
by  their  connection  with  the  tongue.  The  electrolysis  stimu- 
lates the  taste  receptors  and  this  sets  up  a  nerve  impulse  in 
the  taste  nerve.  In  other  woj*ds,  the  impulses  set  up  in  any 
sensory  nerve  are  determined  not  merely  by  the  stimulus, 
but  by  the  make-up  of  the  receptor.  Whatever  the  stimulus, 
the  impulse  is  specific  to  the  receptor  stimulated:  the  taste 


44   OPERATION  OF  THE  NERVOUS  SYSTEM  [ch.  hi 

receptors  always  give  us  tastes,  the  eye  always  gives  us  sensa- 
tions of  light,  —  if  they  give  any  sensation  at  all. 

The  Nerve  Impulse.  —  The  exact  nature  of  the  nerve  im- 
pulse is  not  yet  known.  This  is  because  the  neurons  are  very 
small  and  their  activity  cannot  readily  be  observed.  We 
know  that  nerve  conduction  is  not  a  flow  of  material,  like  the 
passage  of  water  or  gas  through  a  pipe.  We  also  know  that 
the  nerve  impulse  is  always  accompanied  by  an  electric  cur- 
rent; but  it  is  uncertain  whether  this  electric  current  is  the 
nerve  impulse.  There  is  certainly  some  chemical  action  in 
the  neuron  during  the  passage  of  the  nerve  impulse,  and 
possibly  the  nerve  impulse  is  really  a  chemical  change  in  the 
nerve  substance.  In  other  words,  the  nerve  impulse  may  be 
electrical,  or  it  may  be  chemical,  or  it  may  be  a  combination 
of  the  two.  Until  physiologists  have  settled  the  question 
definitely,  psychologists  must  be  content  to  call  the  nerve 
impulse  a  chemico-eledric  event,  which  covers  all  three  possi- 
bilities. 

Properties  of  Neurons :  Excitation  and  Conduction.  —  The 
substance  which  composes  the  neurons  has  a  number  of 
characteristics  or  properties;  its  two  fundamental  properties 
are  excitation  and  conduction.  Excitation  means  that  a  neu- 
ron is  capable  of  being  aroused  into  activity  by  some  force 
acting  upon  its  fine  branching  ends.  A  peripheral  sensory 
neuron  is  excited  by  the  receptor,  as  a  result  of  stimula- 
tion. Every  other  neuron  in  the  arc  is  excited  or  aroused  to 
activity  by  impulses  from  some  other  neuron  which  connects 
with  it  at  a  synapse. 

Conduction  means  that  a  neuron,  when  once  it  has  been 
excited  at  one  end,  transmits  the  impulse  along  its  main  fiber 
and  branches  to  the  synapses  at  its  farther  end.  Conduction 
takes  place  only  in  one  direction.  The  impulse  always  pro- 
ceeds towards  the  center  in  sensory  nerves  and  away  from  the 
center  in  motor  neurons.  This  is  due  to  the  construction  of 
the  synapses.     They  are  so  made  that  the  impulse  can  pass 


CH.  m]  PROPERTIES  OF  NEURONS  45 

through  them  in  one  direction  only  —  like  the  entrance  to  a 
mouse-trap.  The  synapses  of  the  collaterals  follow  the  same 
principle.     They  transmit  impulses  in  one  direction  only. 

The  result  of  this  law  of  conduction  is  that  all  impulses 
tend  to  proceed  from  receptor  to  center  and  from  center  to 
effector.     There  is  no  '  back-wash  '  in  the  reverse  direction. 

Retention  and  Fatigue.  —  The  course  of  the  nerve  impulse 
along  the  arc  is  not  always  the  same.  The  path  which  a 
given  impulse  takes  depends  upon  physiological  conditions 
in  the  neurons  and  synapses.  There  are  two  properties  of  the 
nerve  substance  which  determine  and  alter  the  course  of  the 
impulse:  retention  and  fatigue. 

Retention  means  that  if  an  impulse  in  a  certain  neuron  has 
once  passed  over  a  given  synapse,  that  synapse  thereby  be- 
comes a  less  resistant  or  more  permeable  pathway;  that  is, 
in  future,  similar  impulses  along  this  neuron  are  more  likely 
to  pass  out  through  this  particular  synapse  than  through 
another.  It  also  means  that  every  nerve  impulse  leaves  a 
trace  of  some  sort  in  the  nerve  substance,  which  has  an  effect 
on  future  impulses  passing  along  the  same  neurons.  For 
instance,  when  we  look  at  a  printed  page  the  black  and  white 
of  the  printed  background  stimulate  a  great  many  separate 
neurons;  after  the  impulse  has  passed  on,  the  neurons  retain 
a  trace  or  permanent  impress,  which  influences  any  subse- 
quent impulses  passing  through  these  same  neurons.  This 
permanent  *  set '  or  *  mold  '  is  the  basis  of  memory,  one  of  the 
most  important  facts  in  mental  life.  The  retention  traces  or 
set  left  in  certain  central  neurons  by  the  letters  and  words  we 
have  read,  make  it  possible  for  us  in  future  to  recall  our 
former  experience  of  reading  these  words  —  to  get  a  mental 
image  of  the  same  words  and  sentences  long  afterwards, 
without  consulting  the  book. 

The  persistence  of  retention  is  readily  observed  in  the  case 
of  motor  habits,  such  as  swimming  or  bicycle  riding.  If  you 
once  acquire  one  of  these  habits,  it  can  be  revived  after  a 


46  OPERATION  OF  THE  NERVOUS  SYSTEM  [ch.  hi 

long  lapse  of  time  with  very  little  practice.  The  same  is  true 
of  mental  habits.  If  you  memorize  a  poem  by  repeating  it 
over  and  over  again,  you  will  find  that  you  can  recall  it  after 
a  long  period  during  which  it  has  apparently  been  forgotten. 

Fatigue  is  an  eflFect  which  is  the  opposite  of  retention.  It 
means  a  loss  of  eflSciency.  Through  constant  use  of  the  same 
neurons  and  synapses  there  comes  about  a  wear  and  tear  of 
substance,  which  impedes  the  nerve  impulse.  This  effect  is 
similar  to  the  fatigue  that  occurs  in  the  receptors  and  muscles. 
If  you  look  steadily  at  a  bright  object,  the  eye  is  fatigued ;  if 
you  carry  a  heavy  suitcase,  the  muscles  of  the  arm  are 
fatigued.  The  efficiency  of  the  eye  or  the  muscle  is  tempo- 
rarily impaired.  Just  so  the  synapses  in  the  nervous  system 
become  fatigued  if  we  use  the  same  nervous  arcs  constantly. 
A  fatigued  synapse  offers  more  resistance  to  the  passage  of  im- 
pulses; if  the  resistance  is  very  great  the  impulse  is  unable  to 
pass  through  that  synapse  at  all  and  is  shunted  over  another 
synapse  into  another  path.  This  accounts  in  part  for  the 
variety  of  our  actions.  If  the  synaptic  connections  grew 
continually  more  and  more  fixed,  we  would  in  time  have  only 
a  lot  of  stereotyped  habits. 

The  fatigue  effect  occurs  only  when  the  same  neurons  are 
used  steadily,  with  no  let-up.  If  the  stimuli  are  varied,  the 
synapses  have  a  chance  to  rest,  the  nerve  substance  is  gradu- 
ally restored,  and  the  fatigue  finally  wears  off.  This  is  quite 
different  from  the  retention  effect,  which  persists  in  spite  of 
the  lapse  of  time. 

This  explains  why  we  become  fatigued  after  studying  the 
same  subject  for  a  long  time  without  intermission.  By 
changing  our  mental  work  to  something  quite  different,  we 
rest  the  brain  and  can  accomplish  more. 

Collection  and  Distribution.  —  These  are  two  other  charac- 
teristics or  properties  of  the  nerve  impulse.  Collection  is  the 
gathering  together  of  several  impulses  into  a  single  neuron. 
[Fig.  17.]     When  we  look  at  any  object,  a  great  number  of 


CH.  m]  PROPERTIES  OF  NEURONS  47 

nerve  impulses  are  started  along  the  various  fibers  of  the 
optic  nerve  and  proceed  separately  to  the  visual  center  of  the 
brain.  Here  the  separate  impulses  are  gathered  together,  so 
that  we  see  the  object  as  a  single  thing.  All  our  perceptions 
of  objects  and  events  are  due  to  the  collection  of  many  separ 
rate  impulses. 

Distribution  is  the  opposite  of  collection.  Nerve  impulses 
do  not  always  proceed  along  a  single  pathway.  Often  they 
pass  out  of  a  neuron  by  several  synapses  at  once,  into  as  many 
different  motor  paths.     [Fig.  18.]     Whenever  you  perform  a 

A.,     g.^  S.      B..       ^ 


'  A.'  g:  S.  B, 

Fig.  17.  —  CoLLEcnoN  of  Pig.  18.  —  Distribution  of  a 

Nebve  Impxjlseb  Nkrve  Impulse 

Nerve  impulses  in  two  separate  neu-  The  nerve  impulse  in  neuron  A  di- 

lons  Ai,  At,  passing  through  synapses  vides  and  passes  out  through  the  syn- 

Sti  Si.  enter  the  same  neuron  B  and  apses  Si  and  S2  into  two  separate  neu- 

proceed  onward  as  a  single  complex  ron  paths  Bi  and  Bg. 
nerve  impulse. 

compUcated  movement,  involving  several  muscles,  distribu- 
tion of  the  motor  impulse  takes  place.  When  you  grasp  a 
stick,  all  your  fingers  work  at  the  same  time.  If  you  watch 
the  movement  carefully,  you  will  see  that  the  several  joints 
of  each  finger  bend  at  once;  there  may  be  a  wrist  movement 
also.  This  complicated  movement  is  brought  about  by  the 
distribution  of  the  nerve  impulse  from  a  motor  center  into  a 
number  of  motor  neurons  leading  to  different  muscles. 

Distribution  may  also  occur  in  the  sensory  nerves.  When 
you  are  startled  by  a  sudden  noise,  the  nerve  impulse  is  dis- 
tributed; part  goes  directly  into  the  motor  nerves  and  causes 
the  reflex  movement  of  jumping  or  *  starting  ';  the  rest  of  the 
impulse  passes  up  to  the  higher  auditory  center  and  enables 
you  to  hear  the  noise. 

Importance  of  these  Properties.  —  The  six  characteristics 


48  OPERATION  OF  THE  NERVOUS  SYSTEM  [ch.  m 

just  described  are  properties  of  neurons  and  nerve  substance. 
They  indicate  just  what  difiFerent  operations  the  nervous 
system  can  perform.  The  stimuli  and  receptors  furnish 
certain  material  for  the  use  of  the  nervous  system:  light 
waves  strike  the  eye;  sound  waves  affect  the  ear;  pressure 
stimulates  the  touch  corpuscles,  and  so  on.  How  does  the 
nervous  system  use  this  material?  It  is  able  to  make  use  of 
the  stimuli  in  the  following  ways:  (1)  The  neurons  are  excited 
in  various  ways,  according  to  the  quality,  intensity,  and 
duration  of  the  stimiJus.  (2)  The  impulse  caused  by  the 
stimulus  is  conducted  along  the  peripheral  sensory  neuron  to 
the  next  neuron,  and  so  on  through  the  entire  nervous  arc 
to  the  effector.  (3)  The  effect  of  an  impulse  is  retained  for 
future  use,  through  the  trace  or  set  which  it  leaves  in  the 
nerve  substance.  The  route  of  an  impulse  in  the  nervous 
arc  is  in  part  determined  by  the  traces  left  by  former  im- 
pulses. (4)  Synapses  become  fatigued  through  constant  use, 
which  makes  possible  a  shunting  of  the  impulse  into  other 
paths,  giving  variety  to  our  experience  and  actions.  (5) 
Impulses  from  several  neurons  are  collected  or  gathered  to- 
gether into  a  single  neuron,  producing  complex  nerve  im- 
pulses and  unified  experiences.  (6)  An  impulse  may  be  dis- 
tributed into  several  different  motor  neurons,  which  makes 
possible  the  performance  of  coordinated  movements.^ 

These  properties  belong  not  only  to  the  individual  neurons, 
but  to  the  groups  of  neurons  called  nerves,  and  in  fact  to  the 
nervous  system  as  a  whole.  If  you  examine  your  own  every- 
day experiences,  you  will  find  that  they  all  depend  partly 
upon  the  stimulation  of  yoiu*  eyes,  ears,  skin,  and  other 
receptors,  partly  upon  the  properties  of  the  nervous  system 
just  described.  Memory,  perception,  in  fact  every  event  of 
mental  fife,  can  be  described  in  terms  of  these  fundamental 
properties.^ 

*  Another  property,  less  important,  is  tnodification.    When  several  im- 
pulses combine  they  may  undergo  changes  of  quality. 

*  This  will  be  brought  out  more  fully  in  ch.  vL 


CH.  Ill]  RESPONSE  49 

Response.  —  A  response  is  the  effect  produced  by  nerve 
impulses  upon  the  muscles  and  glands,  together  with  the 
bodily  movements  and  changes  brought  about  by  muscular 
and  glandular  activity. 

Winking  is  an  example  of  a  simple  response;  it  involves 
only  the  muscle  of  the  eye-lid.  Grasping  with  the  hand  is 
more  complex;  it  is  brought  about  by  nerve  impulses  from  the 
centers  to  the  muscles  of  all  the  joints  of  the  fingers  and  thumb. 
Most  of  our  common  acts  are  very  complex  responses.  Take 
the  act  of  reading  aloud.  The  stimuli  are  the  printed  words 
on  the  page.  A  very  intricate  series  of  nerve  impulses  is  set 
up  when  you  look  at  the  letters,  and  the  final  result  is  a  suc- 
cession of  vocal  utterances  due  to  contraction  of  the  muscles 
of  your  throat,  lips,  cheeks,  and  thorax.  Many  human  re- 
sponses are  even  more  complicated  than  this.  When  a  man 
goes  out  from  his  home  town  to  set  up  in  business  or  engage 
in  a  profession  elsewhere,  his  *  going '  is  a  response  to  a 
tremendous  number  of  stimuU  that  have  acted  on  him,  often 
for  a  number  of  years. 

Our  actions  are  called  responses  because  they  are  our 
answers  to  situations  in  which  we  are  placed,  and  which  are 
made  known  to  us  by  stimuli  from  the  environment  affecting 
our  receptor  organs.  All  movements  which  are  produced 
through  the  activity  of  our  nervous  system  are  due  directly 
or  indirectly  to  stimuli.  No  nerve  impulse  is  started  inside 
the  nervous  system;  every  nerve  impulse  originates  in  some 
stimulus  which  works  upon  our  receptors  and  sensory  nerves. 
Even  our  voluntary  actions  are  responses  to  situations  in  the 
outer  world;  these  situations  are  reported  to  the  brain  by 
sensory  nerves,  and  arouse  perceptions  and  thought,  leading 
finally  to  volition. 

The  term  response  as  used  in  psychology  applies  only  to 
movements  or  changes  brought  about  by  the  action  of  the 
individual's  own  nervous  system.  If  we  stumble  over  a  wire 
and  fall,  the  falling  movement  is  not  a  response;  but  the  wild 


50  OPERATION  OF  THE  NERVOUS  SYSTEM  [ch.  in 

gestures  we  make  in  trying  to  save  ourselves  are  responsive  in 
character.  When  a  convict  is  taken  to  prison,  his  going  there 
is  not  a  response,  psychologically  speaking,  though  each  of  the 
steps  he  takes  may  be  a  separate  response.  Going  to  prison 
may  be  a  social  response,  and  falling  down  is  certainly  a 
physical  response,  but  neither  of  these  is  a  psychological  re- 
sponse. Psychology  is  concerned  only  with  actions  which 
are  brought  to  pass  through  the  workings  of  the  nervous 
system. 

Responses  are  of  two  sorts  —  muscular  and  glandular. 
Muscular  responses  are  due  to  contraction  of  the  muscles. 
[Fig.  19.]  When  a  motor  nerve  impulse  reaches  the  muscle 
it  causes  a  chemical  change  in  the  muscle   fibers,  which 


Fia.  19.  —  Muscle  with  Nerve 
Endings 

The  long  horizontal  strips  are  strands  of 
muscle  fibers.  The  dark  vertical  lines  are 
motor  nerve  fibers  which  terminate  in  the 
several  strands.  Nerve  impulses  cause  the 
strands  to  contract  —  they  become  shorter. 
[After  Dunlap.] 


Pig.  20.  —  Diagram  of  Muscu- 
lar Contraction 

A.  Strands  of  an  uncontracted  muscle. 

B.  Same  muscle  when  contracted.  The 
strands  are  shorter,  the  muscle  is  thicker 
in  the  nuddle. 


shortens  them  lengthwise;  the  ends  are  brought  nearer  to- 
gether. The  muscle  is  thickened  in  the  middle  at  the  same 
time.  [Fig.  20.]  One  end  of  the  muscle  is  often  fastened 
to  a  bone  which  plays  in  a  socket,  so  that  when  the  muscle 
contracts  the  bone  turns  like  a  hinge. 


CH.  in]  RESPONSE  61 

Muscles  usually  go  in  pairs.  The  flexor  muscle  bends  the 
arm  at  the  elbow,  the  extensor  straightens  it.  Such  a  pair  are 
called  antagonistic  muscles.  The  name  is  somewhat  mislead- 
ing, for  the  two  antagonists  usually  work  together  splendidly. 
When  one  contracts  the  other  relaxes,  so  that  the  arm  or 
finger  or  other  member  bends  at  a  regular  rate  and  is  held 
securely  in  position  all  the  time  by  the  pair. 

A  muscle  may  be  contracted  at  various  rates  of  speed. 
These  differences  depend  on  the  intensity  of  the  nerve  im- 
pulse. A  quick  bending  of  the  finger  is  brought  about  by  an 
intense  motor  impulse;  a  very  slow  movement  occurs  if  the 
impulse  is  weak  but  continues  to  operate  for  some  time. 
Differences  in  quality  of  the  nerve  impulse  have  not  the  same 
importance  in  motor  nerves  as  in  sensory  nerves.  The  muscu- 
lar contraction  is  the  same  whatever  the  kind  of  impulse. 

In  addition  to  the  motor  nerve  endings  there  are  receptors 
and  sensory  nerves  in  the  muscles.  These  report  to  us  how 
the  contraction  is  progressing.  When  you  are  bending  your 
finger  you  know  all  the  time  how  the  finger  is  moving  and 
how  much  it  has  moved,  even  without  looking.  These 
muscle  sensations  enable  you  to  regulate  the  response.  K 
you  start  to  lift  a  box  and  it  is  heavier  than  you  thought,  the 
sensory  nerves  in  your  arm  muscles  report  to  you  the  amount 
of  resistance  and  the  fact  that  the  movement  is  slow.  There- 
upon a  more  intense  motor  impulse  is  sent  down  to  the 
muscle  and  the  movement  is  speeded  up. 

Glandular  resjponses  are  not  so  important  in  mental  life  as 
muscular  responses.  The  glands  are  more  concerned  in 
growth  and  in  maintaining  the  body  than  in  responses  to  the 
environment.  When  the  glands  take  part  in  our  responses  it 
is  generally  in  a  subsidiary  way.  In  extreme  emotion  we 
weep  —  a  response  by  the  tear  glands.  Anxiety  sometimes 
affects  the  sweat  glands.  The  sight  of  a  luscious  peach  pro- 
duces activity  of  the  salivary  gland;  the  mouth  waters.  It 
has  been  found  also  that  certain  emotions  operate  on  the 


52  OPERATION  OF  THE  NERVOUS  SYSTEM  [ch.  in 

ductless  glands  inside  the  body,  though  these  glands  are 
chiefly  concerned  with  nutrition  and  growth.  Fear  brings 
about  the  production  of  chemical  substances  (such  as  adre- 
nalin) in  the  body,  which  affect  our  general  bodily  condition. 

The  ordinary  operations  of  the  glands  are  not  part  of  the 
response;  in  general,  the  secretion  of  saliva,  urine,  sweat, 
tears,  etc.,  are  part  of  our  bodily  hfe-processes  and  are  of  no 
special  concern  to  psychology. 

Central  Adjustment.  —  In  chapter  i,  the  brain  was  likened 
to  a  telephone  exchange,  where  wires  come  in  from  every  di- 
rection and  are  connected  up  with  a  vast  number  of  other 
wires.  It  may  also  be  likened  to  a  great  switching-yard, 
where  freight  trains  come  in  and  are  broken  up,  some  cars 
going  to  one  destination,  some  to  another.  Both  of  these 
analogies  are  imperfect,  for  nerve  impulses  travel  along  any 
given  nerve  only  in  one  direction:  in  the  sensory  nerves  the 
impulses  always  proceed  inward,  toward  the  cord  and  brain, 
while  along  the  motor  nerves  they  only  travel  out  from  the 
brain  and  other  centers.  Also,  many  impulses  are  always 
coming  in  from  all  directions  at  once,  and  many  complicated 
motor  impulses  are  being  sent  out,  all  at  the  same  moment. 
But  the  main  point  in  the  two  analogies  is  correct:  the  brain 
is  a  great  receiving,  switching,  and  distributing  center  — 
with  many  thousand  times  more  connections  than  exist  in  any 
telephone  central  or  railroad  freight-yard. 

The  brain  centers  and  the  lower  centers  in  the  cord  are  the 
regions  where  the  nerve  impulses  from  the  receptors  are 
switched  over  to  the  motor  nerves  and  sent  out  to  the  effect- 
ors. In  addition  the  brain  centers  collect  many  sensory  im- 
pulses and  distribute  impulses  to  many  motor  neurons.  Both 
of  these  processes  are  of  the  utmost  importance. 

The  collection  of  nerve  impulses  in  the  brain  is  called 
integration.  It  is  more  than  a  mere  addition  process;  the 
separate  impulses  are  put  together  in  such  a  way  that  their 
relations  closely  resemble  the  relations  along  the  stimuli. 


CH.  in]  CENTRAL  ADJUSTMENT  58 

When  we  look  at  a  landscape  the  integrated  affect  of  the 
visual  impulses  in  the  brain  is  like  the  landscape  outside  of 
us  which  stimulates  our  eyes  and  optic  nerves  at  the  moment. 
The  resulting  picture  or  perception  of  the  landscape  —  the 
way  it  appears  to  us  —  is  like  the  real  landscape  in  form. 
This  is  due  to  the  integration  of  separate  impulses  from  a 
large  number  of  nerve  fibers  in  the  visual  center.  We  see 
things  for  the  most  part  as  they  actually  are.  The  same  is 
true  of  hearing,  touch,  and  other  sense  impressions. 

In  looking  at  a  landscape  you  will  notice  that  some  objects 
are  featured  —  they  stand  out  and  attract  our  attention. 
This  means  that  the  nerve  impulses  are  not  collected  uni- 
formly. Some  are  reinforced  and  others  are  weakened,  so 
that  the  various  parts  of  the  visual  field  are  of  different 
vividness  —  they  receive  different  emphasis.  When  you  are 
reading  an  interesting  story  you  do  not  hear  the  conversation 
going  on  around  you.  The  impulses  coming  through  the  ear 
reach  the  brain,  but  they  are  almost  shut  out  from  the  general 
assembly  of  your  impressions  at  the  time.  Here  again  some 
of  the  impressions  are  featured  at  the  expense  of  others. 

Integration  is  the  systematic  assembling  and  marshaling  of 
all  the  impulses  which  reach  the  brain  at  a  given  moment. 
In  the  integrating  process  some  elements  are  focused  and 
others  are  scarcely  noticed.  This  selective  character  of 
integration  is  an  important  factor  in  the  regulation  of  re- 
sponses. If  you  are  gunning,  the  great  idea  is  to  hit  the 
partridge  —  not  to  shoot  up  the  landscape  generally.  You 
must  pick  out  the  bird  from  all  other  details  of  the  scene 
before  you  can  respond  properly.  This  is  accomplished  by 
the  integration  of  sensory  impulses  in  your  brain. 

The  other  important  feature  of  the  brain's  work  is  the 
proper  distribution  of  motor  impulses.  This  is  called  co- 
ordination. It  is  one  thing  to  see  your  bird,  and  quite  another 
thing  to  wing  him.  When  you  raise  the  gun,  the  various 
muscles  of  your  shoulder,  elbow,  wrist,  and  finger  joints  must 


54  OPERATION  OF  THE  NERVOUS  SYSTEM  [ch.  ra 

be  contracted  just  so  much  and  no  more.  If  you  continue 
the  motor  impulse  to  any  of  these  muscles  too  long  or  press 
the  trigger  too  soon,  you  miss  your  shot.  In  order  to  per- 
lorm  any  complex  response  correctly,  the  brain  must  start  a 
number  of  impulses  along  different  motor  paths  at  the  same 
time,  and  each  impulse  must  be  regulated  to  the  proper  in- 
tensity and  must  continue  just  so  long.  Coordination  in- 
volves all  this.  It  is  more  than  mere  distribution  —  it  means 
systematic  distribution. 

One  generally  thinks  of  his  movements  and  voluntary 
actions  as  being  performed  by  his  muscles.  As  a  matter  of 
fact  the  muscles  are  merely  our  agents.  They  are  controlled 
by  our  brain  centers.  Coordination  is  a  brain  process,  not  a 
muscular  process.  It  is  a  question  of  sending  the  right  motor 
impulses  out  from  the  brain  to  the  right  muscles  at  the  right 
time. 

The  two  processes  of  integration  and  coordination  work 
together.  All  our  responses  to  stimuli,  except  in  the  very 
simplest  cases,  involve  them  both.  Most  of  our  actions 
depend  on  a  great  number  of  changing  stimuli  and  are  ac- 
complished by  a  series  of  complicated  movements.  We  must 
learn  to  fit  the  response  to  the  situation.  This  means  inte- 
gration of  all  the  stimuli  and  coordination  of  all  our  motor 
activities.  The  systematic  combination  of  integration  and 
coordination  is  called  adjustment.  We  are  continually  ad- 
justing oxu"  actions  to  constantly  changing  situations. 

The  hunter  shooting  at  the  bird  is  a  case  of  adjustment. 
Until  he  sees  the  bird  there  is  no  impulse  to  pull  the  trigger. 
For  a  time  he  sees  all  sorts  of  other  objects  in  the  landscape. 
Suddenly  he  spies  the  bird;  the  perception  is  due  to  an  in- 
tegration of  many  stimuli  from  the  retina  of  the  hunter's  eye. 
At  once  the  nervous  activity  in  the  hunter's  brain  passes  over 
to  motor  centers  and  out  through  various  motor  nerves  to  his 
arm  and  fingers,  so  that  he  lifts  the  gun  and  pulls  the  trigger. 
The  adjustment  process  here  includes  the  integrated  percep- 


CH.  in]  CENTRAL  ADJUSTMENT  55 

tion  and  the  coordinated  motor  imyndse,  both  of  which  take 
place  in  the  brain.  Adjustment  is  the  most  important  feature 
of  mental  hfe. 

It  is  important  to  keep  this  in  mind  in  reading  the  following 
chapters;  we  shall  take  up  a  great  many  special  topics:  sensa- 
tions (the  elementary  impressions  derived  from  stimuli), 
experiences  of  various  sorts,  and  different  kinds  of  behavior. 
These  separate  facts  are  simply  fragments  of  our  mental  life. 
Mental  life  as  a  whole  is  a  continuous  succession  of  stimula- 
tions leading  to  responses.  The  significant  part  of  the  proc- 
ess is  the  central  adjustment  of  the  response  to  the  stimidus. 
Mental  life  is  not  the  fact  that  we  see,  or  that  we  act,  but  the 
fact  that  our  actions  are  adjusted  to  what  we  see;  the  adjust- 
ment takes  place  in  the  brain. 

Summary.  —  The  nervous  system  serves  as  a  network  of 
pathways  over  which  nerve  impulses  pass  from  the  receptor 
organs  through  the  centers  to  the  muscles  and  glands.  The 
nerve  activity  starts  with  stimulation  of  a  receptor.  This 
produces  an  impulse  in  the  sensory  neurons  which  travels 
along  the  sensory  paths  to  sensory  centers  in  the  cord  and 
brain.  In  the  sensory  centers  impulses  are  integrated  and  pass 
over  to  motor  centers,  where  coordinated  motor  impulses  are 
set  up  in  the  motor  nerves.  The  motor  impulse  travels  along 
motor  paths  to  the  appropriate  muscles  or  glands,  and  dis- 
charges its  energy  into  them;  the  activity  of  these  effectors 
constitutes  a  response. 

The  nerve  impulse  varies  in  intensity  and  quality,  these 
two  characteristics  being  determined  in  the  first  place  by  the 
nature  of  the  stimuU  and  receptors.  There  are  also  certain 
properties  of  the  nerve  substance  which  determine  what  the 
impulse  shall  be,  over  and  above  the  stamp  which  it  receives 
from  the  stimulus.  These  properties  are  excitation,  conduc- 
tion, retention,  fatigue,  collection,  and  distribution. 

The  activity  of  the  nervous  system  proceeds  through  a 
circuit  or  arc  from  receptor  to  effector.    Each  arc  is  composed 


66   OPERATION  OF  THE  NERVOUS  SYSTEM  [ch.  ra 

of  three  sections:  sensory,  central,  and  motor.  Corresponding 
to  these  there  are  three  phases  of  activity:  stimulation,  a^ 
justment,  and  response.  The  adjustment  process  is  the  most 
important  of  all.  It  includes  integration  of  sensory  impulses, 
and  coordination  of  motor  impulses.  Integration  and  co- 
ordination work  together  and  tend  to  make  our  responses 
appropriate  to  the  total  situation  at  any  given  time.  Ad- 
justment is  the  most  significant  fact  of  mental  life. 

PaAcncAL  Exercises: 

11.  Describe  one  of  your  earliest  definite  recollections  of  childhood.  How 
old  were  you  when  it  occurred?  Can  you  tell  why  the  recollection  has 
persisted? 

12.  Try  to  memorize  a  definition  when  sleepy.  Compare  this  with  memo- 
rizing when  you  are  fresh  and  wide  awake. 

13.  Practice  keeping  a  ball  tossing  in  the  air  with  a  tennis  racquet.  Notice 
the  adjustments  of  your  own  movements  to  the  different  angles  of  the 
falling  ball,  and  describe  the  experience. 

14.  Study  several  cases  in  which  you  can  readily  perform  two  independent 
actions  at  once,  and  other  cases  where  one  action  interferes  with 
another.  Compare  them  and  determine  if  possible  why  they  cooperate 
or  interfere. 

15.  Observe  a  child  trying  to  use  knife  and  fork  or  fold  a  napkin.  Describe 
any  lack  of  coordination  that  you  notice. 

[Exercise  11  is  on  retention,  12  is  on  fatigue,  13  on  adjustment,  14 
and  15  on  coordination.] 

Refehences: 
On  the  nerve  impulse:  K.  Lucas,  Conduction  of  the  Nervous  Impulse. 
On  the  operation  of  the  nervous  arc:  C.  S.  Sherrington,  Integrative  Action 
of  the  Nervous  System, 


CHAPTER  IV 

THE  SENSES:  SIGHT 

The  Receptors  and  Sensation.  —  We  have  seen  that  mental 
Ufe  depends  upon  nerve  impulses  which  are  started  by  activity 
in  the  receptor  organs.  All  our  experiences  and  actions  may 
be  traced  to  some  stimulation  of  these  organs  by  objects  or 
forces  outside  our  body  or  by  conditions  within  the  body. 
Before  taking  up  the  study  of  perceptions,  memories,  thoughts, 
and  other  sorts  of  experience,  we  must  examine  the  simple 
elements  of  which  every  experience  is  composed,  and  which 
are  aroused  by  the  activity  of  the  receptors  and  sensory 
nerves.  These  mental  atoms  which  combine  into  experiences 
are  called  sensations. 

The  receptors  are  commonly  known  as  sense  organs  or 
senses.  Formerly  man  was  supposed  to  have  only  five 
senses  —  that  is,  five  distinct  sense  organs,  each  giving  a 
different  sort  of  sensation.  Popular  psychology  and  poetry 
stiU  recognize  only  the  senses  of  sight,  hearing,  taste,  smell, 
and  touch.  Scientific  investigation  has  shown  that  there  are 
several  more.  At  present  we  can  distinguish  eleven  senses, 
with  the  possibility  that  some  of  these  may  be  subdivided 
still  further.     [Table  I.l 

The  senses  fall  into  three  groups:  (1)  the  external  senses, 
which  are  stimulated  by  objects  outside  the  body;  (2)  the 
internal  or  systemic  senses,  which  are  stimulated  by  condi- 
tions within  the  body;  and  (3)  the  motor  senses,  which  are 
stimulated  by  our  movements  and  bodily  position,  and  de- 
pend on  both  the  outer  world  and  oiu*  own  body.  The 
external  senses  fall  into  two  subgroups:  (a)  distant  senses, 
which  are  affected  by  stimuli  usually  originating  in  objects 
situated  some  distance  away  from  our  body,  and  (6)  con- 


58 


THE  SENSES 


[CH.  IV 


^ 


tigtious  senses,  which  are  stimulated  only  by  objects  in  im- 
mediate contact  with  the  body. 


Table  I.  —  Classification  of  the  Senses 


Class 
1.  External 
(o)  Distant 


(6)  Contiguous 


2.  Systemic 


3.  Motor 


I 


Sense  Receptor  Kinds  of  SenscUion 

5  Sight  Eye  Colors  and  grays 

Hearing  Ear  Tones  and  noises 

Smell  In  nostrils  Odors 

r  Taste  In  tongue  Tastes 

J  Touch  In  skin  Contact  and  pressure 

I  Warmth        In  skin  Warmth 

L  Cold  In  skin  Cold 

5  Organic         In  internal  organs  Hunger,  fatigue,  sex,  etc. 
(  Pain  Free  nerve  endings  Pain 

(  Kinesthetic  In  muscles  Efifort,  strain,  etc. 
"s      (muscle  sense) 
t  Static            Semicircular 
canals,  sacs 


Position,  rotation,  etc. 


Sight  is  a  distant  sense.  The  things  that  we  see  are  often 
far  away.  In  reading,  we  hold  the  book  several  inches  from 
the  eye.  The  sounds  that  we  hear  and  the  odors  that  we 
smell  are  from  sources  some  distance  off.  In  every  case  the 
stimulus  must  reach  the  receptor  before  it  can  start  a  nerve 
impulse  and  cause  a  sensation.  But  in  the  case  of  the  distant 
senses  the  stimulus  is  a  wave  or  emanation  from  some  object 
which  does  not  itself  come  into  contact  with  our  body  at  all. 
By  means  of  these  senses  we  gain  information  about  things 
that  lie  at  a  considerable  distance  from  the  body.  This  is 
extremely  important,  for  it  widens  our  field  of  experience 
tremendously :  our  environment  is  extended  as  far  as  we  can 
see,  and  hear,  and  smell.  One  who  is  both  blind  and  deaf 
has  a  very  limited  environment  compared  with  the  normal 
human  being. 

1.  Sight  (Vision) 

The  Eye.  —  The  receptor  for  sight  is  the  eyeball,  together 
with  the  muscles  attached  to  it,  which  enable  it  to  move. 
The  eye  is  a  nearly  spherical  body.     [Fig.  21.]     Its  outer 


CH.  IV] 


STRUCTURE  OF  THE  EYE 


59 


coating  is  a  tough  substance  called  the  sclerotic,  which  covers 
all  the  sphere  except  the  extreme  front  surface.    The  sclerotic 


Pupil 
Iris 

Accomtnodatiorv 
muscle 


Limit 
retina 


Sclerotic 
Choroid 

Retina 
'Fovea 

Optic  nery/e 

Fig.  21.  —  Cross-Section  of  Eye 

Horizontal  section  through  right  eye,  viewed  from  above.    In  left  eye  the 
optic  nerve  pierces  the  retina  at  the  right  of  the  fovea. 

is  almost  impervious  to  light.  The  front  surface  of  the  eye- 
baU  is  covered  by  a  transparent  coat  called  the  cornea.  Light 
passes  readily  through  the  cornea,  just  as  it  does  through  a 
window-pane. 

Looking  at  the  eye  from  the  front,  we  observe  back  of  the 
cornea  a  transparent  oval  body  called  the  lens.  The  lens  is 
convex  on  both  surfaces,  like  a  camera  lens,  and  focuses  the 
light  waves  on  the  rear  inner  surface  of  the  eyeball.  The 
lens  is  held  in  place  by  a  ring-shaped  muscle  at  its  edge,  which 
serves  also  to  change  its  shape.  When  this  accommodation 
muscle  contracts,  it  squeezes  the  lens  so  that  it  bulges  out; 
this  changes  the  focus.     The  space  between  the  lens  and 


60  SIGHT  [CH.  IV 

cornea  is  filled  with  a  transparent  liquid  called  the  aqueous 
humor,  which  permits  the  bulging  of  the  lens. 

The  iris  is  a  flat  muscle  situated  just  in  front  of  the  lens. 
It  resembles  a  disk  or  circular  curtain  with  a  large  hole  in  the 
middle.  The  iris  is  opaque,  and  serves  to  regulate  the  light 
entering  the  eye,  like  the  diaphragm  of  a  camera.  No  light 
can  reach  the  lens  except  through  the  central  hole  of  the  iris. 
This  hole  is  called  the  pupil.  Bright  light  causes  the  iris  to 
contract,  so  that  the  opening  becomes  smaller,  and  less  light 
is  admitted.  When  we  go  into  a  dark  room  the  iris  relaxes 
and  the  opening  becomes  very  large;  more  light  is  admitted 
into  the  eye  and  we  see  more  clearly.' 

Behind  the  lens,  filling  most  of  the  interior  of  the  eye,  is  a 
tough,  transparent,  jelly-like  substance  called  the  vitreous 
body,  which  prevents  the  lens  from  slipping  backward. 

Back  of  the  vitreous,  forming  the  inner  surface  of  the  eye- 
ball, is  the  retina.^  [Fig.  22.]  The  retina  is  a  thin  woven 
coat  composed  of  a  network  of  cells  and  tissues  of  various 
sorts.  It  consists  of  ten  layers,  the  most  important  of  which 
is  the  layer  of  rods  and  cones  (marked  9  in  the  figure). 

The  rods  and  cones  are  the  real  receptors  for  visual  stimuli. 
They  are  exceedingly  small  —  from  0.002  to  0.006  mm.  in  di- 
ameter.* Each  rod  and  each  cone  is  connected  with  a  neu- 
ron of  the  optic  nerve.  The  cones  are  shorter  and  thicker 
than  the  rods ;  the  two  can  be  easily  distinguished  in  the  figure. 
If  we  take  a  tennis  ball,  cut  away  about  a  third  of  it,  and  look 
inside  the  remainder,  what  we  see  corresponds  to  the  area  in 
the  eye  covered  by  rods  and  cones.  They  are  crowded  to- 
gether all  over  the  inner  lining  except  in  front. 

Looking  at  the  surface  of  the  retina,  four  regions  should  be 

^  A  cat's  eye  is  extremely  sensitive  to  light.  Notice  that  the  pupil  con- 
tracts to  a  thin,  line  in  bright  daylight;  in  the  dark  it  becomes  very  large. 
This  is  why  a  cat  can  see  quite  well  when  there  is  very  little  light. 

*  Between  the  (outer)  sclerotic  coat  and  (inner)  retina  is  a  third  coat  called 
the  choroid. 

*  A  millimeter  is  about  one  twenty-fifth  of  an  inch. 


CH.  IV] 


STRUCTURE  OF  THE  EYE 


61 


noticed:  the  center,  the  blind  spot,  the  intermediate  field,  and 
the  periphery. 

(1)  Center  of  Retina:  The  center  of  the  retina  lies  at  the 
'  opposite  pole '  of  the  eyeball  from  the  center  of  the  pupil. 


Interior  of  eyeball;  %atreou» 


Exterior  of  eyeball;  choroid  coat 

Fig.  22.  —  Layers  of  the  Retina 

SecUon  through  the  retina,  showing  its  ten  layers  from  the  vitreous  to  the  choroid  coat  just 
inside  the  sclerotic:  (1)  inner  limiting  membrane,  next  to  vitreous;  (2)  layer  of  nerve  fibers;  (3) 
layer  of  nerve  cells;  (4)  inner  molecular  layer;  (5)  inner  nuclear  layer;  (6)  outer  molecular  layer; 
(7)  outer  nuclear  layer;  (8)  outer  limiting  membrane;  (9)  layer  of  rods  (long,  narrow)  and  cones 
(short,  thick);  (10)  pigment  ceU  layer,  attached  to  choroid.  There  are  many  thousands  of  rods 
and  cones,  covering  the  entire  back  inner  surface  of  the  eye;  the  diagram  shows  only  a  few. 
(Based  on  PiersoLl 


SIGHT 


CH,  IV 


A  line  joining  the  center  of  the  pupil  with  the  center  of  the 
retina  passes  through  the  center  of  the  lens  and  through  the 
center  of  the  eyeball.  The  region  about  the  center  of  the 
retina  has  a  yellowish  tinge  and  is  called  the  macula  Ivtea 
(yellow  spot).  It  contains  only  cones  —  no  rods.  Near  the 
center  of  the  macula  there  is  a  depression  in  the  retina  called 
the  fovea  centralis.  Here  the  cones  are  crowded  together 
more  closely  than  elsewhere.  The  result  of  this  crowding 
is  that  we  can  discriminate  fine  lines  and  points  most  sharply 
at  the  fovea.  It  is  the  region  of  clearest  vision.  When  we 
wish  to  examine  any  object  closely  we  turn  the  eye  so  that 
the  picture  of  this  object  falls  on  the  fovea. 

(2)  Blind  Spot:  The  optic  nerve  does  not  distribute  its 
fibers  on  the  outer  surface  of  the  eyeball  in  man  and  other 
vertebrates.  The  whole  nerve  passes  in  bodily,  through  the 
outer  coating  at  the  back  of  the  eye,  and  distributes  its  fibers 
over  the  inner  surface.  In  the  place  where  the  nerye^breaks 
through  the  eyeball  there  are  no  rods  or  cones.  This  region 
ie^5Zm3  spot;  it  is  somewhat  circular  but  irregular  in 
shape,  and  dmersln  different  individuals.     [Fig.  23.]     You 

cannot  see  an  ob- 
ject whose  picture 
falls  on  this  part 
of  your  eye.  The 
blind  spot  lies  some 
distance  to  the  na- 
sal side  of  the  cen 
ter  in  each  eye,  and 
slightly  below  the 
level  of  the  center. 
If  you  look  stead- 
ily at  a  small  mark  on  a  white  surface  with  the  right  eye,  the 
left  being  closed,  a  figure  somewhat  to  the  right  of  the  fixa- 
tion point  will  not  be  seen  at  all.  [Fig.  24.]  The  blind 
9pots  of  the  right  and  left  eyes  are  in  different  parts  of  the 


X 

F 


Fig.  23.  —  Map  op  Blind  Spot 

Blind  spot  of  the  author's  right  eye.  Drawn  from  two 
pearly  identical  records  made  a  year  apart.  F  =  fisation- 
point. 


CH.  iv]  STRUCTURE  OF  THE  EYE  63 

retina,  so  that  with  both  eyes  open  we  do  not  notice  any 
break  in  the  field. 

O  '  O 

Fig.  24.  —  How  to  Find  the  Blind  Spot 

Close  the  left  eye.  Hold  the  book  about  6  inches  off  and  look  at  the  star  fixedly  with  right 
eye.  Move  the  book  slowly  to  and  from  the  eye  till  the  right-hand  spot  disappears.  Repeat 
with  right  eye  closed  and  the  left-hand  spot  will  vanish. 

(3)  Intermediate  Field  :_The  region  of  the  retJTia  ^rr>vTirl_ 
the  macula  (except  the  blind  SDot)  ^yntAins  hnth  toAs.  and, 
cones^     The  rods  are  more  numerous  than  the  cones  and 
Surround  them. 

(4)  Periphery:  The  outer  rim  of  the  retina,  toward  the 
front  of  the  eyeball,  is  called  the  periphery.  It  contains  no 
cones,  only  rods.  In  this  region  we  see  things  rather  indis- 
tinctly and  cannot  distinguish  colors;  all  objects  appear 
grayish,  as  in  a  photograph.  This  effect  may  be  observed  by 
closing  one  eye  and  bringing  a  small  bit  of  colored  paper 
slowly  into  the  field  of  the  other  eye  from  behind  your  back, 
taking  care  to  keep  the  eye  fixed  steadily  straight  ahead. 

Eye  Muscles. — Sight  is  assisted  greatly  by  muscular  ad- 
justments. The  iris  and  accommodation  muscles  inside  the 
eyeball  have  already  been  described.  The  iris  regulates  the 
amount  of  light  admitted  to  the  eye,  and  the  accommodation 
muscle  focuses  the  picture  clearly  on  the  retina.  There  are 
also  six  muscles  attached  to  the  outer  surface  of  the  eyeball, 
which  serve  to  move  it  about  in  the  socket  and  keep  it  in 
position.  [Fig.  25.]  These  are  arranged  in  three  pairs. 
One  pair  produce  movements  from  side  to  side,  horizontally; 
they  are  called  the  internal  rectus  and  external  rectus  muscles. 
(The  internal  is  on  the  nasal  side.)  A  second  pair  cause  the 
eyes  to  turn  up  and  down;  they  are  called  the  superior  rectus 
and  inferior  rectus  muscles.  The  third  pair  pass  obliquely 
across  the  eyeball,  one  above  and  the  other  beneath  it;  they 


64 


SIGHT 


[CH.  IV 


are  called  the  superior  oblique  and  inferior  oblique  muscles. 
The  oblique  muscles  assist  in  up  and  down  movements;  they 


Opening  for 

*<•  OCW.OMOrOI|,M.AB0U 

f  H*n.nAto  dUAK  TKioen 


Fig.  25.  —  Eyeball  and  Eye  Muscles 

Right  eye  viewed  from  right  side.  The  external  rectus  muscle  is  in  central  foreground,  the 
internal  rectus  slightly  below  and  behind  it.  The  four  other  muscles  are  shown  above  and  be- 
neath the  eyeball.  Upper  edge  of  optic  nerve  is  seen  just  above  external  rectus.  [From  Smith 
and  Elder.] 

also  hold  the  eyeball  in  place  during  its  movements  and  pre- 
vent it  from  twisting  circularly  like  the  hands  of  a  clock. 

How  the  Eye  Acts.  —  From  every  point  of  a  lighted  surface 
the  rays  of  light  spread  out  in  all  directions:  but  only  those 
that  strike  the  open  pupil  can  pass  into  the  eye  and  stimulate 
the  retina.  Take  for  example  the  point  A,  in  front  of  the  eye 
and  above  the  center.  [Fig.  26.]  A  bunch  of  rays  from  A 
pass  through  the  cornea  and  aqueous,  then  through  the  pupil 
into  the  lens.  On  account  of  the  curved  shape  of  the  lens, 
the  rays  are  bent  together  before  they  pass  into  the  vitreous, 
so  that  they  come  together  at  a  point  (or  focus)  on  the  retina 
at  A'.^     The  rays  from  a  point  B,  below  A,  focus  on  the 

*  If  the  lens  is  too  rounded  (near-sightedness)  or  too  flat  (far-sightedness) 
the  rays  do  not  focus  on  the  retina,  and  the  point  is  blurred.    Eye-glassra  are 


en.  iv]  ACTION  OF  THE  EYE  05 

retina  at  B',  above  A'.  Points  to  the  right  of  A  focus  to  the 
left  of  A',  etc.  In  other  words,  the  picture  of  any  object  is 
completely  inverted  on  the  retina,  Uke  the  image  in  a  camera. 

By  means  of  the  focusing  pro- 
cess each  point  of  the  object  be- 
fore us  stimulates  a  single  rod  or 
cone  on  the  retina.  The  stimu- 
lation is  some  sort  of  chemical  -pia.  26.  —  Focusing  Objects 
action.    Each  nerve  fiber  termi-  on  the  Retina 

nating  in  the  retina  is  excited  in-      Ray*  fro™  a  (dotted  lines)  spread  in 

,..,,,,  ,  ,  all  directions,  but  are  bent  in  by  the  lens 

dlVldUally  Py  a  rod  or  cone,  and  and  meet  at  a'  on  retina.     Rays  from  B 

.  v       _         !!.•_•  1  (broken  lines)  are  focused  at  B'.     Rays 

the    reSUitmg    impulses    are   con-  f^om  points  between  a  and  B  focus  in  the 

veyed  to  the  visual  center  in  the    ^""^  "^y-  8'ving  a  dear  but  inverted 

^  ,  image  on  the  retina. 

brain.     [Fig.  27.]     The  separate 

fibers  come  together  and  form  the  optic  nerve,  which  passes 
out  of  the  eyeball  through  the  blind  spot.  The  optic  nerves 
from  the  right  and  left  eyes  come  together  at  ihe_o;^tic^chiasm, 
where  the  nerve  fibers  from  the  nasal  half  of  each  eye  cross 
over,  while  those  from  the  outer  half  continue  along  on  the 
same  side.  Consequently  the  center  for  the  right  half  of 
each  retina  is  in  the  right  side  of  the  brain,  and  that  for  the 
left  in  the  left  side. 

In  order  to  see  an  object  clearly,  the  picture  on  the  retina 
must  be  focused  accurately.  This  focusing  is  not  done  (as  in 
a  camera)  by  moving  the  sensitive  plate  back  and  forth,  but 
by  changing  the  curve  of  the  lens.  When  we  look  at  objects 
near  by,  the  accommodation  muscle  squeezes  the  rim  of  the 
lens  and  makes  it  more  rounded;  when  we  look  at  things 
farther  off  the  muscle  relaxes  and  the  lens  becomes  flatter.' 
The  change  takes  place  automatically. 

used  to  correct  these  two  faults  —  concave  lenses  for  near-sight,  convex  for 
far-sight. 

^  In  astigmatism  the  accommodation  muscles  contract  irregularly,  so  that 
the  lens  does  not  focus  for  both  axes  at  once.  This  is  corrected  by  eye- 
glasses which  are  more  curved  in  the  horizontal  direction  than  in  the  vertical, 
or  vice  versa. 


66 


SIGHT 


[CH. IV 


Fig.  27.  —  Course  of  the  Optic  Nerve 

The  optic  nerves  (ON)  from  the  two  eyeballs  (E)  run  back  into  the  head  and  meet  at  the  op- 
tic chiasm  (OC).  Fibers  from  the  nasal  half  of  each  retina  cross  (broken  lines  CF);  those  from 
the  outer  half  (unbroken  lines  UF)  curve  out  again  and  proceed  on  same  side  of  head  through 
the  optic  tract  (OT)  to  visual  centers  in  the  brain.  The  lower  visual  center  is  in  parts  of  the 
thalamus  called  the  pulvinar  (P)  and  external  geniculate  body  (EG).  Center  for  touch  sen- 
sations from  eyeliall  is  in  the  upper  quadrigeminal  body  (UQ).  From  the  thalamus,  projec- 
tion fibers  proceed  to  the  higher  visual  center  in  the  occipital  lobe  of  the  cortex  (C). 

N3,  N4,  N5,  =  nuclei  of  III,  IV,  V  cranial  nerves,  for  eye  movement;  GC  =  commissure  of 
Gudden,  connecting  the  lower  visual  centers  on  the  two  sides  of  the  brain.  [Modified  after 
Lickley.]  ^ 


CH.  iv]  ACTION  OP  THE  EYE  e7 

The  iris  muscle  also  works  automatically.  Bright  light 
causes  the  iris  to  contract,  so  that  the  pupil  becomes  smaller. 
The  dazzling  eflFect  of  a  sudden  glare  of  light  is  due  to  the 
fact  that  the  iris  has  not  had  time  to  contract  suflficiently. 

The  muscles  for  eye  movement  work  both  automatically 
and  voluntarily.  An  inherited  system  of  nerve  connections 
controls  their  operation;  when  the  rays  from  a  bright  or 
noticeable  object  fall  on  any  part  of  the  retina  except  the 
center,  the  appropriate  eye  muscles  are  contracted  so  as  to 
turn  the  center  of  the  pupil  directly  toward  this  object. 
This  is  called  involuntary  fixation.  We  also  turn  the  eyes 
voluntarily,  by  contracting  one  of  the  four  rectus  muscles, 
or  by  contracting  one  of  the  horizontal  pair  and  one  of  the 
vertical  pair  at  the  same  time.'  Eye  movement,  whether 
voluntary  or  involuntary,  helps  us  to  see  more  clearly,  since 
the  center  of  the  retina  is  the  region  of  sharpest  discrimina- 
tion. We  see  an  object  best  when  we  fixate  it  on  the  fovea; 
if  the  object  is  in  motion,  we  follow  its  course  with  the  eye, 
keeping  it  on  the  fovea. 

Stimuli  for  Sight. — Jlie  light  rays  which  stimulate  the  eye 
^e  not  material  oartif IpSt  htit  ^^  ves  in  the  ether.  They  are 
exceedingly  minute  and  travel  very  rapidly^  The  largest 
visible  hght  waves  are  only  760  millionths  of  a  millimeter 
Ou/i)^  in  length;  the  smallest  waves  that  affect  the  eye  are 
about  390  nn.  All  light  waves,  whatever  their  length,  travel 
through  the  atmosphere  at  the  same  speed  —  about  300,000 
kilometers  or  200,000  miles  per  second.  This  means  that  a 
greater  number  of  short  waves  reach  any  given  point  every 
second.  In  other  words,  short  waves  have  a  relatively  large 
number  of  vibrations,  long  waves  a  relatively  small  number 
of  vibrations  per  second.     [Fig.  28.] 

When  sunUght,  which  contains  waves  of  all  lengths,  is 

'  There  is  always  some  adjustment  of  all  the  other  muscles  when  the  eye 
moves. 
*  Pronounced  mew-mew. 


f  if/'\ 


5  > 


SIGHT 


[CH.  IV 


passed  through  a  prism  its  direction  is  changed.  This  bend- 
ing is  called  rejractioiu  The  short  waves,  because  they  are 
short,  are  deflected  from  their  course  more  than  the  long,  so 
that  the  different  waves  spread  out  Uke  a  fan.     [Fig.  29.]    If 


Fig.  28.  —  Long  and  Short 
Light  Waves 

The  upper  wave  is  twice  as  long  as  the 
lower.  Since  they  travel  at  the  same 
speed  from  A  to  B,  only  half  as  many  of 
the  long  waves  will  reach  B  in  a  given 
period  of  time.  The  longer  the  wave 
length,  the  fewer  waves  per  second. 


Fig.  29.  —  Refraction  op 
Light 

A  ray  of  sunlight,  containing  waves 
of  all  lengths,  coming  from  S  passes 
through  the  prism  and  is  refracted. 
The  shortest  waves  (violet  end  of  color 
series,  V)  are  bent  most,  longest  waves 
(red  end,R)  least.  They  spread  out  on 
a  reflecting  surface  and  form  a  spec- 
trum of  colors. 


refracted  light  is  thrown  on  a  white  surface  each  wave  length 
gives  a  different  color;  the  entire  series  of  colors  obtained  by 
refraction  is  called  the^^gednm.'  Each  distinguishable  color 
is  caused  by  a  certain  definite  wave4en(]ih  of  light,  —  or  by  a 
certain  uniform  number  of  light  waves  striking  the  eye  every 
second;  we  can  express  it  either  way. 

In  addition  to  their  differences  in  wave-length,  light  waves 
vary  in  intensity^  Bright  light  is  caused  by  more  violent 
vibrations  —  the  waves  swing  farther  from  side  to  side  as 
they  move  along.  Intense  (or  bright)  light  acts  more  power- 
fully upon  the  rods  and  cones  of  the  retina  and  produces  a 
sensation  of  greater  intensity  when  the  resulting  nerve  im- 
pulse reaches  the  visual  center. 

Qualities  of  Visual  Sensations.  —  In  studying  each  of  the 
senses  one  of  the  first  questions  is.  What  are  the  different 
sorts  of  impressions  that  it  gives  us?  So  in  examining  the 
sense  of  sight  we  have  to  determine  the  various  qualities  of 
visual  sensations.  First  of  all,  we  find  two  distinct  groups  of 
sensationS?vCQJorg  and  grays. 

^  The  spectrum  is  seen  in  the  rainbow. 


CH.  IV] 


VISUAL  SENSATIONS 


ro 


Pure  color  sensations,  or  hues,  are  produced  by  stimuli 
which  consist  of  uniform  l^ff^*-  ly^vf^-  If  the  waves  that 
strike  the  retina  are  about  400  nn  in  length  we  see  violet;  if 
they  are  650  or  more  we  see  red.  The  series  of  colors  lies 
between  the  limits  390  and  760  fi/i. 

Qffiy  ■<;*'Tigq^i^"o  oi**^  p'-^diif^'^H  hv  stimuli  of  mixed  light, 
waves  in  which  no  single  wave  prednmina^^^j,  The  piu^  gray 
sensations  form  a  series  of  their  own,  the  extremes  of  which 
are  called  white  and  hlack. 

In  addition  to  these  two  pure  groups  there  is  a  third  class 
of  impure  sensations,  which  combine  in  various  ways  the 
color  effect  with  the  gray  effect.  They  are  produced  by  a 
mixture  of  color  stimuli  with  gray  stimuli.  Most  of  our 
visual  sensations  are  of  this  sort. 

The  relations  of  visual  sensations  to  one  another  may  be 
studied  by  means  of  colored  disks  which  are  fitted  together 
and  placed  on  a  color  mixer.     [Fig.  30.]     When  we  spin  the 


Fio.  80.  —  Color  Mixer 

The  colored  disks  (A)  are  slit  from  circumference  to  center  so  they  can  be 
fitted  together,  with  s  segment  of  each  disk  showing.  The  disks  are  fitted 
around  a  projection  to  the  axis  of  B  and  screwed  fast.  The  mixer  b  rotated  by 
turning  a  handle  C.  By  the  series  of  belts  connecting  the  three  wheels  with  B 
the  speed  of  rotation  is  greatly  increased. 

interiocked  disks  around  very  rapidly,  the  colors  (or  grays) 
blend  together  and  give  an  intermediate  sensation.     If  we 


70  SIGHT  [CH.  IV 

start  with  a  pure  red  disk  and  little  by  little  add  a  segment 
of  yellow,  we  can  determine  just  how  much  yellow  must  be 
added  to  red  in  order  to  produce  a  noticeable  change  in  sen- 
sation. And  so  for  the  changes  from  yellow  to  green,  etc. 
In  the  same  way  we  can  observe  the  just  noticeable  changes 
in  a  gray  series  by  mixing  a  white  disk  with  a  segment  of 
black  or  vice  versa.  The  impure  sensations  are  obtained  by 
combining  each  of  the  pure  color  disks  with  a  black  or  a 
white  or  a  gray  disk  on  the  mixer. 

When  we  have  made  all  possible  combinations  of  colors  and 
grays  on  the  color  mixer  we  shall  have  found  all  the  diflFerent 
qualities  of  visual  sensations.  The  relations  of  these  sensa- 
tions to  one  another  may  be  shown  by  a  diagram  which  takes 
the  form  of  a  spindle.^  [Fig.  31  A.  The  central  cross-sec- 
tion, with  the  belt  of  pure  colors,  is  enlarged  in  Fig.  31  B.] 
Bear  in  mind  that  the  spindle-shaped  figure  represents  only 
the  relations  of  the  colors  and  grays  as  seen  by  the  eye  —  not 
the  relations  of  the  physical  light  waves  which  stimulate  the 
retina.  The  various  visual  sensations  are  represented  on  the 
spindle  as  follows : 

(1)  Hue  or  Color  Tone:  The  relations  of  the  pure  colors 
are  represented  in  the  form  of  an  irregular  belt,  shown  in 
Fig.  31  B.  The  sectors  in  this  diagram  mark  off  the  more 
prominent  hues  —  red,  orange,  yellow,  olive,  green,  peacock 
(or  blue-green),  blue,  and  violet.  Each  of  these  names  really 
applies  to  a  number  of  distinguishable  hues;  for  instance,  even 
in  the  pure  colors  seen  in  the  spectrum  we  can  distinguish 
several  sorts  of  red,  which  look  more  and  more  like  orange; 
then  several  sorts  of  orange  which  look  more  and  more  hke 
yellow,  and  so  on  to  the  extreme  violet. 

There  are  also  a  number  of  hues  which  are  not  produced  by 

single  light  waves,  but  are  due  to  mixing  red  and  violet  light 

in  various  proportions.    These  hues  make  up  the  purple  sector 

of  the  belt.     They  are  just  as  real  hues  and  just  as  simple 

^  It  is  also  called  a  color  cone  or  color  pyramid. 


CH. 


IV] 


VISUAL  SENSATIONS 


n 


VKi^ 


sensations  as  any  others,  though  they  are 
not  due  to  simple  waves.  This  explains 
why  we  represent  the  hues  by  a  continu- 
ous belt  instead  of  by  a  line.  If  we  start 
with  red  and  keep  changing  the  hue  we 
pass  through  all  the  spectral  colors  to  vio- 
let, and  then  through  purple  to  the  red  we 
started  with.  All  told  there  are  about  j^ 
distinguishable  pure  colors,  including  the 
piuple  hues. 

(2)  Shade  or  Brightness:  The  pure 
gray  sensations  are  represented  by  the  cen- 
tral axis  in  Fig.  81  A.    One  end  of  the 


Btadc. 


Fio.  31.  —  Color  Spindle  and  Color  Belt 

A.  Color  spindle:  showing  schematically  the  various  dis- 
tinguishable visual  sensations,  arranged  according  to  shade 
(vertical  direction),  tint  (radii  from  central  axis),  and  hue 
(angles  about  axis).  The  gray  series  is  represented  by  the 
central  vertical  axis.  The  purest  hues  (most  saturated 
color  tones)  lie  on  the  circumference  of  the  color  belt.  The 
relative  proportion  of  shades,  tints,  and  hues  is  indicated 
by  the  relative  number  of  units  assigned  to  each.  (Notice 
the  great  preponderance  of  shade-units  over  others.) 

B.  Color  belt,  enlarged;  showing  relative  number  of  dis- 
tinguishable hues  of  each  spectral  color  and  of  purple;  rela- 
tive saturation  of  the  various  pure  hues  is  indicated  by  dis- 
tances of  the  belt  from  central  gray  axis.  Colors  repre- 
sented by  the  sectors:  Red,  Orange,  Yellow,  Olive,  Green, 
Peacock  (»  blue-gieen),  Blue,  Violet,  Purple. 


n  -  SIGHT  [cH.  rv 

axis  represents  the  whitest  white,  the  other  end  represents 
the  blackest  black.  There  are  about  700  distinguishable  gray 
shades^  between  these  two  extremes. 

A  color  may  be  made  brighter  or  darker  by  mixing  it  with 
white  or  black.  If  we  take  a  red  disk,  for  instance,  and  inter- 
lock it  with  a  white  disk,  the  mixture  is  bright  red.  If  we  put 
a  red  disk  and  a  black  disk  together,  the  mixture  is  a  dark  red. 
These  are  different  color-shades.  The  color-shades  are  repre- 
sented on  the  spindle  by  vertical  Unes  parallel  to  the  gray 
axis. 

Figure  32  A  shows  how  a  series  of  red  color-shades  may  be 
obtained  on  a  single  disk.  Such  a  series  may  be  found  for  each 
distinguishable  color  hue.  A  color-shade  may  be  compared 
with  a  gray-shade  by  interlocking  a  disk  of  each  and  rotating 
them  slowly  on  the  color  mixer.     If  one  is  brighter  than  the 


Fig.  32.  —  Sektes  of  Color-Shades  and  Tints 

A.  Color-shade  series.  —  The  mottled  surface  represents  red.  If  disk  A  be  rotated  on  a 
color-mixer,  we  get  a  series  grading  from  bright  red  at  the  circumference  to  dark  red  at  the  cen- 
ter; same  amount  of  color  (saturation)  everywhere. 

B.  Tint  or  saturation  series.  —  Mottled  surface  represents  red.  If  disk  B  be  rotated,  we  get 
a  series  of  tints  grading  from  pure,  saturated  red  at  the  circumference  to  pale,  unsaturated  red 
ending  in  colorless  gray  at  the  center;  same  amount  of  brightness  (shade)  everywhere. 

other  they  will  flicker;  if  they  are  of  the  same  shade  there  is 
no  flicker  at  all. 

(3)  Tint  or  Saturation:  There  is  still  a  third  way  of 
varying  the  quality  of  visual  sensations,  namely,  by  mixing 
*  Artists  use  the  term  value  instead  of  shade  or  brightness. 


CH.  iv]  VISUAL  SENSATIONS  78 

together  a  pure  color  and  a  gray  in  various  proportions.  If 
the  color  and  the  gray  are  of  the  same  brightness,  these 
mixtures  will  all  be  of  the  same  shade;  yet  they  will  be  quite 
different.  If  the  mottled  portion  of  the  disk  in  Fig.  32  B  is 
reproduced  in  red,  when  the  disk  is  rotated  on  a  color  mixer 
we  observe  a  pure  red  at  the  circumference;  passing  toward 
the  center  we  observe  a  graded  series  in  which  the  color  be- 
comes less  and  less  pronounced;  the  center  is  a  pure,  colorless 
gray.  This  change,  which  is  neither  a  change  of  hue  nor  a 
change  of  shade,  is^alled  saiura^mLU^SL  chrQma»^or  tint^  A 
pure  color  is  said  to  be  *  completely  saturated ' ;  its  saturation 
decreases  as  more  and  more  gray  is  added  to  the  mixture. 
Gray  is  'completely  unsaturated.'  The  partly  saturated 
colors  observed  by  rotating  Fig.  32  B  form  a  series  of  tints. ^ 

The  differences  of  tint  are  represented  in  our  spindle  dia- 
gram by  radii  from  the  axis  toward  the  circumference.  The 
farther  from  the  axis,  the  greater  the  saturation.  It  will  be 
noticed  that  some  of  the  radii  are  shorter  than  others.  This 
means  that  some  pure  colors  in  the  spectrum  are  found  to  be 
less  saturated  than  others.  Yellow,  for  instance,  is  decidedly 
less  saturated  than  violet;  there  are  more  steps  of  difference 
in  passing  from  violet  to  gray  of  the  same  shade,  than  in 
passing  from  yellow  to  gray.  When  any  two  hues  are  mixed 
the  resulting  color  is  less  saturated  than  either  of  them  taken 
separately.  Consequently  the  purple  hues,  which  are  ob- 
tained only  from  mixtures,  are  represented  on  the  belt  by  a 
straight  line.  All  purples  are  relatively  unsaturated;  they 
have  fewer  tints  than  the  spectral  colors. 

Every  visual  sensation  has  a  certain  assignable  position  on 
the  spindle  figm-e.  Every  color  has  a  certain  hue,  shade,  and 
tint.  Gray  has  only  shade;  we  might  say  that  its  saturation 
is  zero.    Our  diagram  also  brings  out  the  fact  that  very  bright 

*  A  vivid  tint  means  that  the  color  is  very  pure  or  saturated.  A  pale  tint 
means  that  the  object  is  mainly  gray,  with  very  little  color;  it  may  be  either 
dark  or  bright  —  that  is  a  question  of  shade. 


74 


SIGHT 


[CH.  IV 


and  very  dark  colors  are  quite  unsaturated;  near  the  white 
and  black  poles  there  are  relatively  few  steps  between  pure 
color  and  gray.     It  is  estimated  that,  all  told,  about  30,000 

visual  quaUties  can  be  distin- 
guished by  the  normal  human 
eye. 

Primary  Colors. — Artists  and 
physicists,  as  well  as  psycholo- 
gists, are  interested  in  the  ques- 
tion of  what  colors  are  primary. 
Newton's  list  of  seven  colors  is 
famiUar  to  every  one;  but  it  has 
no  special  significance.  Newton 
was  misled  by  the  analogy  of  the 
musical  scale  and  thought  there 
must  be  seven  tones  in  the  color 
scale  also.  It  has  long  been 
known  that  by  taking  three  hues 
—  red,  green,  and  blue  —  and 
combining  them  together  on  a 
color  mixer  in  various  ways  any 
hue  can  be  obtained.  This  has 
led  to  the  idea,  which  still  pre- 
vails popularly,  that  these  three 
hues  are  primary  or  fundamental 
colors.  In  a  way  this  is  true. 
But  on  the  other  hand  psycholo- 
gists find  that  yellow  is  quite  as 
distinctive  a  color  as  the  three 
just  mentioned.  It  is  also  a  fact  that  orange,  violet,  and 
indeed  every  separate  hue  in  the  spectrum,  is  a  simple  color 
—  the  result  of  a  simple  stimulus.  Are  there  three  primary 
colors,  or  four,  or  a  hundred? 

A  curious  fact  suggests  the  answer  to  this  question.    If  the 
eye  be  fiixed  on  a  point  straight  ahead,  and  a  small  b!t  of 


Pro.  33.  —  Perimeter 

Observer's  chin  is  placed  on  a  rounded 
chin-rest  at  A,  which  is  so  adjusted  that 
one  eye  is  directly  over  semicircular  top 
of  rod  B,  the  other  eye  being  closed.  A 
smnll  hole  through  the  axis  at  C  serves 
as  fixation  point.  Color  stimulus  is 
moved  on  a  carriage  along  the  semicir- 
cular arm,  D,  of  perimeter  toward  or 
away  from  center.  On  the  back  of  the 
arm  is  a  scale  of  degrees.  The  arm  D 
rotates,  so  that  all  parts  of  the  visual 
field  can  be  explored.  On  outer  side  of 
plate  E  (which  rotates  with  D)  is  fas- 
tened a  chart,  ruled  radially  and  circu- 
larly to  represent  degrees  of  'latitude' 
and  '  longitude '  from  center  of  vision. 
Experimenter  records  the  readings  on 
the  chart,  which  is  hidden  from  observer 
by  E.    [From  Judd,  after  Meyrowiti-l 


CH.  IV] 


PRIMARY   COLORS 


75 


colored  paper  be  moved  slowly  from  the  fixatioii-p>omt  out 
toward  the  periphery,  it  is  found  that  most  colors  change 
noticeably  in  hue  as  they  get  farther  from  the  center.  A  red 
becomes  yellowish,  and  so  on.  But  there  are  four  definite 
hues  which  do  not  alter  in  this  respect.'  These  four  *  invari- 
able '  hues  are  called  primal  colors^  and  may  be  regarded  as 
the  most  primitive  and  representative  hues  of  all;  they  are  & 
certain  definite  blue,  green,  yellow,  and  red.  Curiously 
enough,  primal  red  is  not  a  spectral  hue.  It  is  sHghtly 
purplish.  The  primal  colors  and  the  changes  which  occur  in 
other  hues  near  the  periphery  may  be  observed  by  means  of 
the  perimeter.  [Fig.  33.]  Table  II  shows  the  wave-lengths 
of  the  primal  colors  and  the  wave-lengths  of  the  groups  of 
hues  to  which  popular  names  are  given. 


Table  U. —  Spectral  Lines  and  Color  Range 


Spectral  Line 


A 

Primal  Red 
B 
C 
D2 

Primal  Yellow 

E 
Primal  Green 

F 
Primal  Blue 

Gi 

H 


Wave-Length 

MM 

766.1 


No.  of  Vibrations 

Trillion  per  second 

391.41 


Color 
Hue 


Range 
MM 


Red 


760-647 


Orange        647-588 
Yellow         588-550 


Green 

Blue 

Violet 


550-492 
492-455 
455-390 


687.0  417.06 

656.28  456.91 

589.0  509.01 

577  521 

526.96  569  03 

501  599 

486.14  616.82 

477  629 

432.58  693.19 

396.84  755.62 

Visible  Range:  760-390  MM,  399.55-768.87  trillion. 
Limits  of  Color  Change:  655-430 IM^. 

(Wave-lengths  from  Houstoun,  Treatise  on  Light,  p.  473.  Primal  colors 
from  Titchener,  Exper.  Psychol.,  Vol.  I,  Part  I,  p.  4.) 

Purkinje  Phenomenon  and  Adaptation.  —  Most  of  our 
color  sensations  are  due  to  the  reflection  of  light  from  painted 
surfaces.     The  paint  pigments  absorb  all  rays  except  one 

^  At  the  periphery  they  become  gray,  as  do  all  colors;  but  the  htu  does  not 
Vary  —  it  only  fades  out. 


76  SIGHT  [cH.  IV 

wave-length;  the  reflected  light  is  of  the  hue  corresponding 
to  the  non-absorbed  wave-length. 

The  brightness  of  pigment  colors  varies  with  the  intensity 
of  the  general  illumination.  In  a  darkened  room  all  colors 
appear  darker;  but  the  brightness  of  different  colors  changes 
at  different  rates.  When  the  general  illumination  is  very 
bright,  yellow  and  red  become  relatively  brighter  than  other 
colors.  If  the  room  be  made  very  dark  they  appear  darker 
than  blue  or  green.  This  is  especially  noticeable  if  we  com- 
pare red  with  blue.  |X~red  book-cover  which  appears  much  "* 
brighter  than  a  blue  cover  in  a  well-lighted  room,  will  appear 
darker  when  the  light  is  turned  very  low.  This  peculiar 
.  variation  in  the  relative  brightness  of  colors  is  called  theJ 
^Purkinje  phenomenon,  from  the  man  who  first  reported JtJ 

The  Pur  kin  je  phenomenon  is  part  of  the  process  of  adapta- 
tion to  intense  and  feeble  illumination  which  takes  place  in 
the  retina  itself,  due  to  changes  in  the  condition  of  the  rods 
and  cones.  When  we  go  suddenly  from  darkness  to  bright 
daylight  the  eyes  are  dazzled.  After  a  time  the  eyes  become 
adapted  to  brightness.  In  the  same  way  the  eyes  adapt 
themselves  to  a  darkened  room.  The  process  of  adaptation 
is  greatly  assisted  by  the  iris  reflex. 

There  is  also  adaptation  when  the  general  field  of  vision  is 
tinged  with  some  color.  If  we  put  on  green  glasses  the  whole 
landscape  at  first  appears  green.  After  a  time  this  tinge  dis- 
appears, and  our  outlook  is  apparently  normal,  except  that 
red  objects  appear  gray. 

Complementaries,  After-sensations,  and  Contrast.  —  If  a 
disk  of  yellow  cardboard  and  a  disk  of  blue  be  fitted  together 
so  as  to  give  a  surface  half  yellow  and  half  blue,  and  this  be 
rotated  rapidly  on  a  color  mixer,  the  two  will  tend  to  neu- 
tralize each  other.  If  we  select  a  certain  hue  of  each  and  mix 
them  in  various  proportions,  at  some  point  we  get  a  mixture 
in  which  no  color  effect  whatever  is  observed:  the  disk  appears 
as  a  plain  gray  surface.    For  a  given  yellow,  a  certain  blue 


CH.  IV]      AFTER-SENSATIONS,  CONTRAST  77 

can  be  found  which  yields  this  eflFect.  This  yellow  and  this 
blue  are  called  complementaries  or  complements.^  For  every 
color  hue  in  the  series,  including  the  purples,  one  and  only 
one  complementary  hue  exists. 

If  we  look  steadily  for  about  a  minute  at  a  very  bright 
colored  object  (a  red  blotter,  for  instance)  and  then  turn  the 
eye  quickly  to  a  white  wall,  we  see  on  the  wall  a  patch  of  the 
complementary  color  (bluish  green,  in  this  case).  This  afteiv 
effect  is  called  suieggjj^  .Sfte2^i^?H^^- '^  -"-^  ^^  ^^^  ^^  fatigue 
of  the  portion  of  the  retina  stimulated  by  the  bright  color. 
White  gives  rise  to  a  black  after-sensation,  and  conversely. 
For  this  reason  white  and  black  are  regarded  as  complements. 

After  practice  one  can  get  an  after-sensation  more  readily 
and  hold  it  longer.  If  you  reach  this  stage  you  Will  observe 
another  effect  also;  after  the  eye  is  turned  toward  the  white 
wall  there  appears  first  of  all  a  sensation  of  the  same  color  as 
the  object  you  were  looking  at.  This  is  a  posHiveaJ^&r-sensa- 
^J^n.  It  lasts  only  a  very  short  time  and  then  changes  into 
the  negative.  The  positive  aftosensation  is  due  to  inertia 
of  the  retina. 

Often  a  strong  negative  after-sensation  after  persisting 
some  time  changes  into  a  second  positive,  and  this  again  into 
a  second  negative.  These  effects  are  obtained  only  after 
great  practice  and  under  very  favorable  conditions;  all  except 
the  first  positive  are  due  to  fatigue  and  recuperation  of  the 
retina. 

Complementary  v;ffects  may  be  brought  about  under  cer- 
tain conditions  without  moving  the  eye.  If  we  place  on  a 
color  mixer  a  disk  containing  a  ring  which  is  partly  black  and 
partly  white,  surrounded  by  a  uniform  color  (e.g.,  blue),  when 
the  disk  rotates  the  black  and  white  ring  it  not  seen  as  gray, 
but  is  tinged  with  the  complement  (yellow)  of  the  surrounding 
color.     [Fig.  34.]     A  similar  effect  is  obtained  by  placing  a 

^  The  latter  is  a  term  recently  suggested  by  Christine  Ladd-Franklin. 
'  It  is  also  called  an  after-image. 


78 


SIGHT 


[CH.  IV 


Fig.  34.  —  Contrast  Color 

Mottled  surface  represents  blue.  Ro- 
tating the  disk,  the  black  and  white 
ring  is  tinged  with  yellow;  if  instead  of 
blue  tne  mottled  surface  is  red,  the  ring 
takes  on  a  greenish  tinge. 


bit  of  gray  paper  on  a  colored  blotter  and  covering  the  whole 
with  white  tissue  paper.  Theappearanpe  of  axomplementary 
eSect  _withoitt  ev£  movemeni.  js^JS^^Qd^sinmltaneous  contrast^ 

The  complementary  color  which 
appears  around  the  borders  of  a 
colored  figure  on  a  white  back- 
ground when  the  eyes  wander  is 
a  negative  after-sensation.  It  is 
called  successive  contrast. 

Color  Blindness.  —  A  consider- 
able proportion  of  persons  show 
striking  pecuHarities  of  color  sen- 
sation. They  fail  to  distinguish 
between  certain  hues  which  lie 
far  apart  in  the  spectrum,  such  as 
red  and  green.  This  defect  is 
called  color  blindness.  Ask  a  color- 
blind person  to  hand  you  the  red 
book  on  the  table  and  he  is  just  as  likely  to  hand  you  a  green 
book.  You  think  he  is  joking;  but  really  he  is  acting  in  per- 
fectly good  faith; — he  cannot  tell  the  difference  between  red 
and  green.  Color  blindness  is  due  to  something  in  the  make- 
up of  the  retina.  Just  what  this  is  no  one  has  yet  been  able  to 
discover.  It  is  not  a  diseased  condition  of  the  eye;  for  cer- 
tain types  of  color  blindness  are  inherited,  like  the  color  of 
the  hair  or  shape  of  the  fingers.  It  seems  rather  to  be  the  sur- 
vival of  a  primitive,  less  developed  type  of  eye  which  may 
have  been  universal  in  mankind  before  color  vision  became 
perfected. 

The  most  common  form  of  color  blindness  is  inherited  in  a 
pecuhar  way.  It  is  found  chiefly  in  males.  The  sons  of  such 
a  color-blind  person  do  not  inherit  the  peculiarity,  and  his 
daughters  inherit  only  the  latent  possibility.  They  are  not 
color  blind  themselves,  but  their  sons  are  color  blind.  In 
other  words,  this  form  of  color  bUndness  is  transmitted  from 


CH.  iv]  COLOR  BLINDNESS  TO 

a  man  to  his  daughter's  sons.  There  are  also  forms  of  color 
blindness  which  appear  in  women  as  well  as  men. 

Color  blindness  is  either  total  or  partial.  A  totally  color- 
blind person  sees  everything  like  a  photograph;  the  world 
appears  to  him  in  black  and  white  and  shades  of  gray,  with- 
out any  color  whatever.     This  form  is  quite  rare. 

There  are  three  distinct  varieties  of  partial  color  blindness, 
which  are  popularly  called  red,  green,  and  blue  blindness. 
Blue  blindness  is  rare  and  is  possibly  due  to  some  diseased 
condition  of  the  retina.  In  this  form  the  person  is  unable  to 
distinguish  between  blue  and  yellow. 

Red  and  green  blindness  are  the  most  common  forms.  In 
each  there  is  confusion  between  red  and  green.  But  the  two 
forms  are  distinct.  This  is  demonstrated  if  we  ask  the  person 
to  tell  us  how  the  spectrum  looks  to  him.  A  red-blind  indi- 
vidual sees  nothing  at  all  at  the  red  end  of  the  spectrum.  The 
green-blind  person  sees  something  throughout  the  spectrum, 
but  he  confuses  red  and  green  with  yellow. 

How  do  we  know  just  what  the  colors  look  like  to  a  partially 
color-blind  man?  Our  description  would  seem  to  be  mere 
guesswork.  But,  as  it  happens,  cases  have  been  found  in 
which  one  eye  is  color  blind  and  the  other  eye  normal.  Such 
persons  are  able  to  compare  the  sensations  of  their  two  eyes 
and  to  translate  the  abnormal  eye  into  terms  of  the  normal. 

Color  blindness  raises  certain  very  practical  issues.  On 
the  railroads  and  at  sea  the  two  colors  red  and  green  are  com- 
monly used  as  signals.  It  is  sometimes  a  matter  of  life  and 
death  to  distinguish  them  clearly  and  immediately.  A  color- 
blind engineer  may  make  a  fatal  mistake.  Many  tests  have 
been  devised  to  determine  color  blindness.  Some  of  these 
are  open  to  serious  objection.  Color-blind  persons  can  dis- 
tinguish difiFerences  of  shade  very  accurately.  If  only  a  few 
standard  cards  are  used  in  the  test,  one  may  learn  to  dis- 
tinguish these  particular  cards  by  their  shade  and  so  pass 
the  test. 


80  SIGHT  [CH.  IV 

A  test  devised  by  Stilling  meets  this  objection.  It  consists 
of  a  set  of  cards  with  a  great  many  round  colored  spots  of 
various  sizes  and  shades  scattered  about  promiscuously. 
Most  of  the  spots  on  each  card  are  of  one  color  (say,  red),  with 
a  few  of  the  other  color  (green)  interspersed.  The  green 
spots  are  arranged  in  the  form  of  numerals,  so  that  a  normal 
person  will  see  immediately  and  clearly  the  number  37  (or 
whatever  it  is)  in  the  pattern.  A  color-blind  person  looking 
at  the  card  can  see  only  the  differences  of  shade:  he  cannot 
pick  out  the  number,  but  will  trace  some  entirely  different 
pattern.     It  is  practically  impossible  to  fool  this  test. 

/Color  Zones.  —  At  the  periphery  of  the  eye  color  qualities 
/'disappear  even  in  normal  persons.  We  are  all  color  blind  in 
this  region.  Unless  the  stimuli  are  exceptionally  bright 
everything  looks  gray,  like  a  photograph,  at  about  90  degrees 
in  any  direction  from  the  point  on  which  the  eye  is  fixed. 
Some  colors  disappear  before  others.  Green,  for  instance,  is 
limited  to  a  much  smaller  region  than  blue  or  red.  The 
region  in  which  we  can  see  any  color  is  called  the  zone  for  that 
color.  These  color  zones  are  determined  by  means  of  the 
perimeter.'  A  map  of  the  color  zones  in  a  typical  eye  is 
shown  in  Fig.  35. 

Visual  Intensity.  —  In  sight,  changes  in  intensity  or  bright- 
ness are  closely  related  to  the  gray  series  of  qualities.  White 
is  always  very  intense:  black  is  of  faint  intensity.  The 
Purkinje  phenomenon  and  adaptation  may  be  treated  as  in- 
tensity relations. 

Experimental  psychology  is  interested  in  two  problems  of 
visual  intensity:  (1)  What  stimulus  produces  the  least  ob- 
servable visual  intensity,  or  brightness?  (2)  What  change  of 
stimulus  gives  rise  to  the  lea^t  observable  change  in  brightness? 
These  same  questions  crop  up  in  every  one  of  the  senses. 
The  least  observable  changes  in  sensations  will  be  treated  to- 
gether after  we  have  finished  our  study  of  the  separate  senses.^ 
1  See  Fig.  S3,  p.  74.  »  See  p.  146-149. 


CH.  IV] 


VISUAL  mTENSITY 


81 


The  least  observable  visual  brightness  may  be  determined 
as  follows :  The  observer  is  placed  in  a  darkroom  with  black- 


FiG.  35.  —  Color  Zones  of  the  Retina 

limita  at  which  four  colors  disappear  in  passing  from  center  of  eye  toward  periphery, 
determined  for  radii  30  degrees  apart.    Right  eye. 

ened  walls.  On  a  dull  black  surface  before  him  a  pencil  is 
fixed  upright.  A  light  of  standard  brightness  is  moved  slowly 
toward  the  pencil  from  a  distance,  till  the  subject  just  barely 
observes  the  shadow  cast  by  the  pencil.  The  faint  light 
bordering  on  the  shadow  is  called  the  least  observable  bright- 
ness. Certain  visual  processes  occur  in  the  retina,  however, 
even  when  no  stimulus  is  present;  we  often  see  dust  clouds  or 
spots  of  light  when  our  eyes  are  closed  in  the  dark.  So  that 
this  experiment  really  measures  the  brightness  of  the  objec- 
tive stimulation  which  is  just  observably  different  from  the 
eye's  own  retinal  light.    According  to  Langley  the  energy  of 


8«  SIGHT  [CH.  IV 

the  light  which  produces  the  least  observable  visual  sensation 
under  most  favorable  conditions  is  0.000,000,03  ergs. 

Explanation  of  Visual  Qualities.  —  Many  facts  in  the  sense 
of  sight  are  peculiar  and  diflBcult  to  explain :  Why  do  the  two 
extremes  of  the  spectrum,  red  and  violet,  look  somewhat 
alike?  How  is  it  that  purple,  a  simple  color,  is  not  found  in 
the  spectrum?  Why  is  yellow  a  distinctive  color,  though  it 
is  not  among  the  three  that  are  sufficient  to  produce  every 
hue  by  mixture?  How  can  we  account  for  the  various  sorts 
of  color  bUndness,  and  the  wide  prevalence  of  color  blindness 
in  the  human  race?  Why  is  the  periphery  of  the  retina  color 
blind  even  in  the  normal  eye? 

Most  puzzUng  of  all  is  the  sensation  of  black.  Black  is  as 
much  a  sensation  as  white  or  any  of  the  color  hues;  yet  it  is 
not  due  to  stimulation  by  light  waves  at  all.  It  is  aroused 
when  no  Ught  stimulates  that  particular  portion  of  the  retina, 
though  to  get  a  distinct  black  sensation  some  nearby  region 
must  be  stimulated  by  light. 

These  extraordinary  facts  indicate  beyond  question  that 
the  processes  in  the  retina  are  very  complicated.  Even  to-day 
they  are  not  understood.  The  explanations  suggested  are 
only  partly  satisfactory;  they  do  not  cover  all  the  facts. 

The  penetio  thf  "^Y  "^  sjpht.  which  was  devised  by  Christine 
Ladd-Franklin,  seems  tofit  the  facts  best.  This  explanation 
starts  with  the  notion  that  color  vision  has  evolved  gradually 
from  a  more  primitive  type  of  eye  which  could  see  only  shades 
of  gray.  It  supposes  that  there  exists  in  the  rods  and  cones 
a  certain  substance,  which  when  stimulated  by  light  arouses 
sensations  of  gray  and  white.  This  substance  occurs  in  the 
retina  in  the  form  of  particles  called  color  molecules.  In  the 
primitive  eye  only  gray  and  white  were  distinguished. 

In  the  course  of  evolution  the  color  molecules  in  the  cones 
became  differentiated  into  two  components,^  one  of  which 

*  The  color  molecules  in  the  rods  are  not  differentiated:  they  give  gray 
only. 


CH.  iv]      THEORY  OF  VISUAL  QUALITIES  83 

when  stimulated  yields  sensations  of  blue,  while  the  other 
yields  sensations  of  yellow.  Later  on  in  history  the  yellow 
component  became  diflFerentiated  in  turn  into  two  compo- 
nents, one  yielding  red,  the  other  green.  So  in  the  fully 
developed  eye  there  are  four  primal  colors :  red,  yellow,  green, 
and  blue.  But  since  red  and  green  are  derived  from  yellow, 
yellow  is  not  essential  to  color  combinations  like  the  other 
three.  This  theory  explains  why  red  and  green  color  blind- 
ness are  comparatively  common,  and  why  the  normal  eye 
does  not  distinguish  colors  peripherally:  in  color-blind  per- 
sons the  color  molecules  are  only  partly  developed;  and  the 
periphery  is  capable  of  giving  only  sensations  of  gray  because 
this  region  has  no  cones. 

The  Ladd-Franklin  theory  seems  to  cover  all  the  perplexing 
phenomena  of  sight  except  the  sensation  of  black.  The  best 
plan  is  to  accept  this  view  as  a  partial  explanation,  recogniz- 
ing that  it  does  not  tell  the  whole  truth.^ 

One  conclusion  is  forced  upon  us  more  and  more  as  we 
study  the  sense  of  sight:  this  sense  has  by  a  long  process  of 
evolution  developed  an  exceedingly  complicated  organ,  which 
has  come  to  fit  our  needs  most  admirably.  It  furnishes  us 
with  a  vast  number  of  elementary  sensations  which  give  an 
incalculable  variety  to  our  experiences.  We  can  see  very  fine 
distinctions  of  color  and  shade.  We  can  distinguish  very  fine 
Unes  and  points.  We  can  observe  objects  at  a  very  great 
distance  from  our  body  by  means  of  sight.  Of  all  the  senses, 
sight  has  the  greatest  practical  importance  in  human  life. 

Practical  Exercises: 

16.  Describe  the  after-sensations  of  color  obtained  by  looking  across  the 
room  at  a  window-sash  on  a  bright  day,  and  then  closing  the  eyes,  or 
turning  them  to  a  dull  gray  surface. 

17.  Describe  your  experience  of  visual  adaptation  on  going  suddenly  from 
a  very  light  to  a  very  dark  room  and  vice  versa.  Note  especially  the 
Purkinje  phenomenon  (p.  76). 

^  There  are  two  other  important  color  theories,  one  devised  by  Yoxmg  and 
Helmholtz,  the  other  by  Hering. 


84  SIGHT  [cH.  IV 

18.  Test  the  limits  of  your  color  zones  for  red,  yellow,  green,  and  blue. 
This  requires  assistance.  The  test  should  be  made  in  a  room  with 
white  walls.  Cut  out  small  bits  of  each  color  and  place  one  at  a  time 
on  a  black  or  white  strip  of  cardboard.  The  assistant  brings  the  color 
gradually  in  from  right  or  left  till  the  color  is  recognized.  Test  one 
eye  at  a  time,  with  the  other  eye  bandaged. 

19.  Make  a  map  of  some  one's  blind  spot.  Bandage  one  eye  and  fix  his 
head  by  a  head-rest  fifteen  inches  from  the  wall.  Place  a  sheet  of 
white  paper  on  the  wall,  marking  a  cross  in  the  middle  for  fixation 
point.  Make  a  pointer  of  white  cardboard,  with  the  tip  (one-eighth 
inch  square)  blackened,  and  move  it  slowly  across  the  paper.  Mark 
in  pencil  each  spot  where  the  black  tip  disappears  or  reappears. 

20.  Examine  various  colored  objects  in  your  room,  including  surface  of 
walls,  tables,  chairs,  and  floor.  Describe  their  shade  in  five  grades: 
very  bright,  bright,  medium  shade,  dark,  very  dark.  Describe  their 
tint  (saturation)  in  three  grades:  very  pure  color,  medium  saturation 
(much  gray),  slight  tinge  of  color  (very  pale). 

21.  With  eyes  closed  place  the  blocks  in  the  form-board  (p.  175).  Notice 
the  length  of  time  required  and  the  errors  made.  Repeat  with  eyes 
open,  and  compare  the  two  performances, 

[Exercise  20  is  on  visual  qualities;  21  is  on  the  relative  importance 
of  sight  and  touch;  the  other  exercises  are  self-explanatory.) 

References: 

On  the  eye:  Ladd  and  Woodworth,  Physiological  Psychology,  pp.  182-196. 

On  visual  sensations,  color  blindness,  etc.:  J.  H.  Parsons,  Introduction  to 
the  Study  of  Color  Vision;  E.  A.  Schaefer,  Text-book  of  Physiology,  article 
on  'Vision';  M.  Greenwood,  Physiology  of  the  Special  Senses;  chs.  10-20. 

On  visual  theories:  C.  Ladd-Franklin,  in  Mind,  N.S.  1893,  2.  473-489; 
Parsons,  op.  cit.;  Greenwood,  op.  cii. 


CHAPTER  V 
THE  SENSES:  HEARING  AND  OTHER  SENSES 

2.  Hearing  (Audition) 

The  Ear.  —  The  human  ear  is  a  very  complicated  organ. 
The  pecuUar-shaped  shell  to  which  the  name  ear  is  popularly 
applied  is  only  an  insignificant  part  of  the  apparatus  for  hear- 
ing. It  merely  collects  the  stimuli  and  directs  them  into  the 
proper  channel.     The  real  ear  Ues  inside  the  head. 

The  receptor  for  hearing  is  divided  into  the  outer  ear, 
middle  ear,  and  inner  ear.     [Fig.  36.]    The  outer  ear  consists 


Levator 
<  rnuftcl» 


Fig.  36.  —  Ceoss-Section  op  Eab 

Vertical  lecUon  ai  right  ear  through  meatus  and  Eustachian  tube,  viewed  from 
front  of  bead. 

of  the  gfeg/f,(concha).  together  with  a  tube,  about  an  inch  long, 
called  the  meatus,  which  leads  into  the  head  through  an  open^ 


86  HEARING  [ch.  v 

ing  in  the  skull  and  ends  in  a  vibrating  membrane  called  the 
ear-drum  (tympanic  membrane). 

The  middle  ear  lies  beyond  the  drum.  It  is  a  small  cavity 
in  the  head,  containing  three  small  bones  which  take  up  and 
transmit  the  vibrations  from  the  drum.  The  middle-ear 
cavity  is  the  end  of  a  passage  (the  Eustachian^  tvM)  which 
opens  into  the  back  of  the  mouth.  If  the  drum  is  pressed 
back  too  far  into  the  middle-ear  cavity  by  a  tremendous 
sound,  we  may  remedy  the  trouble  by  swallowing,  which 
forces  air  into  the  Eustachian  tube  and  pushes  the  drum 
forward  into  place.  In  the  bony  wall  of  the  middle-ear 
cavity,  opposite  the  drum,  are  two  apertures,  called  the  (yvQ,l 
tmj^QwjkU^.  round  vdndow.  They  are  not  open;  but  each  is 
fitted  with  a  vibratmg  membrane,  which  permits  the  sound 
waves  to  pass  through,  just  as  the  glass  in  a  window-pane 
admits  light  waves. 

The  three  small  bones  of  the  middle  ear  form  a  chain.  The 
hammer  bone  (so  called  because  it  is  shaped  like  a  rude, 
primitive  hammer)  is  attached  to  the  center  of  the  drum  at 
the  handle  end,  and  at  the  middle  is  held  in  place  by  a  tendon. 
The  head  of  the  hammer  fits  into  the  second  bone,  called 
the  amril;  and  the  anvil  attaches  to  the  arch  of  the  stirrup 
bone,  whose  base  is  attached  to  the  membrane  of  the  oval 
window. 

The  sound  waves  gathered  by  the  shell  of  the  ear  pass 
through  the  meatus  and  set  the  drum  in  vibration.  This 
vibration  affects  the  handle  of  the  hammer;  the  hammer  being 
pivoted  in  the  center,  its  head  beats  on  the  anvil,  which  jars 
the  stirrup,  and  this  sets  the  membrane  of  the  oval  window 
vibrating  in  exact  measure  with  the  original  sound  waves. 
But  this  is  not  all.  The  crucial  process  of  hearing  takes  place 
in  the  inner  ear. 

The  inner  ear  or  labyrinth  is  a  very  complicated  cavity, 
only  part  of  which  is  concerned  with  hearing.  [Fig.  37.]  The 
portion  toward  the  back  of  the  head  contains  the  semicircular 


CH.  V] 


THE  EAR 


87 


canals,  which  are  receptors  for  the  static  sense;  ^  they  have_ 

nothing  to  do  with  hearing.    The  front  part  of  the  labyrinth 

contains     a     spiral  v  yy 

structure  resembling  \     ^/f^^'^SSt 

the  shell  of  a  snail,  ^*^  /^:^»»«. 

called    the    cochlea, 

which   contains   the 

real     receptor     for 

hearing.       Between 

the  canals  and  the 

cochlea  is   a  cavity 

called  the  vestibule. 

The  inside  of  the 
cochlea  is  divided 
into  two  spiral  tubes, 
lying  side  by  side, 
which  run  from  the 
base  to  the  tip  of  the 
cochlea.      [Fig.   38.] 

They  are  separated  by  a  membrane,  except  at  the  top,  where 
they  unite.  Between  these  two  tubes  (called  the  scala  tym- 
pani  and  sccda  vestibuli)  is  a  smaller  tube  called  the  cochlear 
duct,  which  is  separated  from  them  by  membranes.  In  a 
small  canal  within  the  cochlear  duct  is  a  system  of  minute 
rods  and  ha^celjs,  called  the  OTgana[_Corjli.  [Fig.  39.]  These 
rods  and  hair  cells  connect  with  the  iSbers  of  the  auditory 
nerve,  and  are  the  real  receptors  for  hearing. 

.  We  traced  the  course  of  the  stimulus  through  the  chain  of 
bones  as  far  as  the  oval  window.  The  vibrations  of  the  mem- 
brane in  this  window  set  up  waves  in  the  liquid  that  fills  the 
cochlea.  These  waves  pass  up  the  scala  vestibuli,  which 
starts  at  the  oval  window;  at  the  apex  of  the  cochlea  they  go 
over  into  the  scala  tympani  and  pass  down,  finally  reaching 
the  round  window  at  the  base.     (The  round  window  serves 

1  See  p.  117. 


Fig.  37.  —  Labyrinth  of  the  Ear 

Enlarged  view  of  labyrinth  in  nearly  the  same  plane  as 
Fig.  36.  Semicircular  canals  at  left,  cochlea  at  right;  be- 
tween them  the  two  windows  and  vestibule.  [From  Smith 
and  Elder.) 


88 


HEARING 


[CH.  V 


noLF^Iep, 


merely    as    a    shock-absorber.)      During    the    passage    of 
the  waves   through   the  cochlea  the  cells  of  Corti  are  set 

into  sympathetic 
vibration.  They 
are  of  different 
lengths,  and  each 
picks  up  certain 
«  ;•.'  ■  mimmiLas^m.'^^  \^^  ■■x'fli/iii iiiHf  waves  of  corre- 
^^  "'^ifcCTff?^iB Bsll^    J^IUm^       sponding  length, 

just  as  the  strings 
of  a  piano  rever- 
berate to  sounds 
of  their  own 
length.  When  a 
wave  of  a  given 
length  passes 
through  the  coch- 
lea, it  sets  in 
vibration  the  ap- 
propriate rod  or 
hair  cell  of  Corti, 
and  this  stimu- 
lates a  certain 
fiber  of  the  auditory  nerve,  which  carries  a  nerve  impulse  up 
to  the  auditory  center  in  the  brain. 

There  is  no  muscular  apparatus  for  focusing  sounds  in  the 
human  ear,  such  as  we  have  in  the  eye.  A  rudimentary 
muscle  exists  for  lifting  the  ear,  but  it  is  rarely  used  and  in 
most  persons  is  not  under  control  of  the  will.  We  can  focus 
sounds  slightly  by  turning  the  head  so  as  to  make  the  effect 
clearer  and  more  distinct. 

Stimuli  for  Hearing.  —  The  stimuli  for  hearing  consist  of 
vibrations  called  sound  waves.  These  waves  are  very  much 
more  sizable  than  light  waves  and  diflFer  from  them  in  many 
other  respects.     Sound  waves  travel  through  the  air  at  the 


Fig.  38.  —  Section  through  Cochlea 

The  cochlea  cut  open  from  apex  to  base  near  the  central  core 
(modiolus)  at  right  angles  to  plane  of  Figs.  36  and  37.  The  apex 
or  tip  of  cochlea  is  at  left  of  the  drawing.  Section  shows  three 
windings  of  scala  tympani  (right)  and  scala  vestibuli  (left). 
The  cochlear  duct  (not  shown)  lies  between  the  two  scalee  away 
from  the  core;  it  is  bounded  by  two  membranes  which  form  a 
continuation  of  the  spiral  lamina  (Lam.  spiral,  ossea).  [From 
Smith  and  Elder.] 


CH.  V] 


STIMULI  FOR  HEARING 


uniform  rate  of  332.4  meters  (about  1000  feet)  a  second.  Like 
light  waves  they  differ  from  one  another  in  length.  The 
longer  the  sound  wave,  the  fewer  waves  strike  the  ear-drum 


membrana  tectoria 


outer  h&ir  cells 


ntrve  fibres 


inner  rod  ^**  'P'""*'* 

basilar    membrane 
Fig.  39.  —  Organ  of  Cohti 


cells  ef  Deitera 
outer  rod 


'•^'^SLs^ 


Section  perpendicular  to  direction  of  windings  of  the  seals.  Rods  of  Corti  are  designated 
'inner  rod,'  'outer  rod.'  The  rods  and  hair  cells  become  longer  in  successive  sections  toward 
apex  of  cochlea.    [From  Lickley,  after  Retzius.] 

in  a  given  period  of  time.  It  is  customary  to  measure  sound 
waves  in  terms  of  the  number  per  second  instead  of  wave 
length.'  The  greatest  frequency  (rate  of  vibration)  of  sound 
waves  that  the  average  man  can  hear  is  about  30,000  per 
second;  the  lower  limit  is  about  12  or  16.  The  rate  of  vibra- 
tion determines  the  quality  of  sensation. 

Sound  waves  may  be  started  in  three  different  ways:  (1) 
by  twanging  a  tightly  stretched  violin  string,  which  being 
elastic  vibrates  to  and  fro;  or  by  tapping  a  tuning  fork  or  the 
membrane  of  a  drum.  (2)  They  may  be  started  by  blowing 
into  a  tube,  which  sets  the  air  into  vibration  at  different  rates 
according  to  the  length  of  the  tube.      (3)  A  third  way  of 

*  Because  the  number  of  waves  per  second  is  the  same  for  any  given  sound, 
whether  the  vibration  is  of  air  particles  or  strings;  the  wave  length  would 
vary  with  the  density  of  the  medium. 


90  HEARING  [ch.  v 

starting  sound  waves  is  by  tapping  a  rigid  body,  such  as  a 
bell  or  xylophone;  here  the  rate  of  the  sound  waves  depends 
on  the  size  and  material  of  the  body,  not  on  its  elasticity. 
In  every  case  the  sound  waves  are  eventually  communicated 
to  the  air  and  so  to  the  ear-drum.  The  only  exception  is 
where  a  vibrating  fork  is  pressed  against  our  head;  the  sound 
waves  are  then  transmitted  directly  through  the  bones  of  the 
skull  to  the  drum. 

Sound  waves  differ  not  only  in  frequency  (vibration  rate) 
but  also  in  intensity.  The  same  sound  (e.g.,  middle  C  on  the 
piano)  may  be  faint  or  loud,  depending  on  the  force  of  the 
disturbance  in  the  air.  If  you  pluck  a  violin  string  vigor- 
ously, the  air  particles  do  not  move  any  faster,  nor  vibrate 
more  times  per  second,  but  they  swing  more  violently  back  and 
forth  with  each  vibration.  This  results  in  a  louder  sound  — 
not  in  a  different  quality  of  tone. 

Qualities  of  Auditory  Sensation.  —  Just  as  in  sight,  there 
are  different  quahties  of  auditory  sensation  for  the  various 
rates  of  vibration,  and  there  are  also  sensations  due  to  mixed 
rates.  A  uniform  sound  vibration  gives  a  tone  sensation; 
mixed  vibrations  give  a  noise. 

The  parallel  between  sight  and  hearing  is  not  complete. 
A  noise  is  not  pleasant  like  gray  light;  and  noises  do  not  form 
an  independent  series  like  the  grays  —  every  noise  is  more  or 
less  like  some  tone  whose  vibration  rate  predominates  in  the 
mixture.  Strike  a  table  in  different  places  and  you  will 
notice  that  the  resulting  noises  are  somewhat  like  dull,  flat 
tones. 

Tones  and  Pitch.  —  If  we  snap  a  tuning  fork,  the  prongs 
vibrate  to  and  fro  uniformly,  at  a  rate  which  depends  on  the 
length  of  the  fork.  This  vibration  causes  uniform  sound 
waves  in  the  air,  and  the  resulting  sensation  is  not  a  noise 
but  a  tone.  A  long  fork  vibrates  at  a  slow  rate  —  that  is,  few 
times  per  second;  it  gives  a  deep  tone.  A  shorter  fork  vi- 
brates at  a  more  rapid  rate  and  the  resulting  tone  is  more 


CH.  v]  AUDITORY  SENSATIONS  91 

shrill.'  The  vibration  rates  between  12  and  30,000  give  a 
series  of  about  11,000  distinguishable  tones.  The  difference 
in  quality  between  tones  is  called  difference  in  pitch,  and  the 
whole  series  of  audible  tones  is  called  the  auditory  scale. 
Tones  and  pitch  correspond  to  colors  and  hue  in  the  sense  o* 
sight.  We  ask,  "  What  is  the  pitch  of  that  tone.?*  "  just  as  wc 
ask,  "  What  is  the  hue  of  that  color?  " 

The  relations  of  tones  to  one  another  is  quite  diflferent  from 
the  relations  of  colors.  In  the  first  place  tones  have  not  so 
much  individuality.  Take  the  tone  produced  by  256  vibra- 
tions, which  is  called  middle  C  on  the  piano  and  is  used  as  a 
standard.^  Most  persons  are  quite  unable  to  identify  it.  If 
you  ask  a  man  to  hum  C,  he  is  likely  to  give  something  quite 
different;  if  you  strike  several  notes  on  the  piano,  he  is  unable 
to  tell  which  is  C.  Color  recognition  is  much  more  developed. 
No  one  who  is  not  color  bUnd  finds  any  diflficulty  in  picking 
out  a  green  from  a  red  or  a  yellow.  This  lack  of  individuality 
in  tones  is  probably  the  reason  why  they  have  never  received 
distinctive  names  like  the  colors.  They  are  called  by  the 
uninspiring  names  A,  B,  C,  etc. 

A  few  persons  are  able  to  recognize  tones  as  accm*ately  as 
colors.  They  can  tell  whether  a  piano  is  tuned  slightly  above 
or  below  the  usual  standard.  This  ability  is  called  recogni- 
tion of  absolute  pitch.  It  is  said  that  Mozart,  when  quite 
young,  went  with  his  father  to  the  house  of  a  musician.  He 
tried  the  man's  violin  and  immediately  noticed  that  it  was 
tuned  a  quarter  tone  above  his  own,  which  he  had  left  at 
home.  Even  among  musicians  the  ability  to  recognize  abso- 
lute pitch  is  rare. 

On  the  other  hand  most  persons  recognize  quite  accurately 
the  relation  between  pairs  of  tones.  When  we  sing  or  hum  or 
whistle  a  tune  the  tones  are  sounded  in  a  certain  order;  it  is 

'  Deep  and  shrill  tones  are  often  called  low  and  high  respectively.  But 
these  terms  suggest  diflFerences  in  intensity  —  faint  (or  low)  and  loud. 

^  This  is  the  standard  in  scientific  work.  Musicians  generally  use  another 
standard,  called  international  pitch,  in  which  middle  C  is  261. 


92  HEARING  [ch.  v 

the  relation  of  the  successive  tones  that  makes  the  tune.  The 
abiUty  to  hum  a  tune  or  to  recognize  it  depends  on  your 
recognition  of  pitch  relations,  or  relative  pitch,  —  not  on  abso- 
lute pitch;  for  the  tune  is  the  same  whether  you  start  with  C 
or  D  or  any  other  tone. 

The  serial  relation  of  tones  is  also  quite  different  from  that 
of  the  color  series.  K  you  strike  middle  C  on  the  piano  and 
then  the  next  key  to  the  right,  and  so  on,  you  will  observe 
that  they  become  continually  "  more  shrill."  But  if  you 
compare  them  in  pairs,  C  :  D,  C  :  E,  C  :  F,  etc.,  you  will  find 
that  some  of  these  pairs  are  more  closely  related  than  others. 
Notice  especially  C  and  C^.  [Fig.  40.]  They  sound  very 
much  alike,  though  they  are  far  apart.  The  vibration  rate 
of  C*  is  just  twice  that  of  C^  This  1:2  relation  is  called  an 
octave.  It  suggests  that  tones  might  be  represented  by  a 
diagram  shaped  like  a  spiral  or  corkscrew,  in  which  any  tone 
lies  immediately  above  (or  below)  its  octave  in  the  next  twist 
of  the  spiral. 

Suppose  we  take  the  tones  C  and  C^  and  all  tones  lying 
between  them.  A  great  many  tones  can  be  distinguished 
within  these  limits,  but  only  a  few  are  used  in  music.  On  a 
piano  there  are  seven  white  keys  starting  with  C ;  the  eighth^ 
key,  C\  begins  a  new  series.  The  eight  tones  included  within 
the  octave,  taken  in  pairs,  give  the  principal  relations  or 
intervals  used  in  tunes  and  in  musical  compositions  generally. 
They  are  chosen  because  the  numerical  proportion  of  their 
vibrations  appeals  especially  to  the  human  ear:  C*  has  256 
and  G^  384  vibrations  per  second;  that  is,  the  relation  of  C 
to  G'  is  2:3;  the  relation  of  C  to  F'  is  3: 4;  and  so  on.  If  you 
examine  Fig.  40  you  will  see  that  the  musical  intervals  within 
the  octave  are  all  represented  by  rather  simple  numerical 
relations  —  the  ratio  numbers  are  small;  15:16  is  the  least 
simple  ratio.2    In  general,  the  simpler  the  numerical  ratio  of 

^  In  Latin  'eighth'  is  'octavus,'  whence  the  word  'octave.' 
*  The  black  keys  on  the  piano  are  used  when  we  take  some  other  tone 
besides  C  as  standard;  we  need  extra  tones  to  fill  in  the  larger  intervals. 


CH.  V] 


AUDITORY  SENSATIONS 


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94  HEARING  [ch.  v 

two  tones,  the  *  closer  '  or  '  more  harmonious  '  is  the  relation, 
whether  the  tones  are  sounded  successively  or  together. 
This  closeness  of  relation  is  something  quite  different  from 
nearness  of  pitch.  The  smallest  pitch  difference  in  music  is 
the  semitone,  or  minor  second,  which  is  the  interval  between 
E  and  F  and  between  B  and  C.  But  this  interval,  whose 
ratio  is  15 :  16,  is  musically  the  least  close  relation  of  all. 

It  is  not  easy  to  explain  why  these  tone  intervals  affect  us 
as  they  do.  The  effect  is  probably  due  in  some  way  to  the 
hair-cells  and  rods  of  Corti;  but  the  full  explanation  is  stiU 
uncertain.  However,  we  shall  see  why  intervals  bearing  a 
simple  ratio  are  pleasanter  than  those  expressed  in  larger 
numbers,  when  we  observe  the  effects  of  two  or  more  tones 
sounded  at  the  same  time. 

Overtones  and  Timbre.  —  When  we  strike  a  key  on  the 
piano  or  blow  a  cornet,  the  sound  waves  are  not  simple. 
Besides  the  vibrations  depending  on  the  length  of  the  string 
or  tube,  there  are  fainter  vibrations  corresponding  to  the 
half-length,  third-length,  etc.  When  we  pluck  a  \4olin  string 
it  vibrates  not  only  as  a  whole,  but  in  half-lengths  if  it  is 
plucked  one-quarter  from  the  end,  and  in  other  part-lengths 
according  to  the  place  where  it  is  plucked.     [Fig.  41.] 

*^^MiruEmma:-*aijjiriEi]Iimi^ 

Fig.  41.  —  How  Overtones  are  Made 

The  solid  line  is  a  violin  string  fastened  at  A  and  B.  Fluck  it  1/6  from  the 
end  (at  arrow)  and  it  vibrates  in  thirds,  besides  vibrating  as  a  whole.  The 
part-length  vibration  is  the  overtone  or  harmonic;  it  is  fainter  than  the  funda- 
mentaL     ( The  amount  of  '  waver  '  is  exaggerated  in  the  figure.) 

These  lesser  tones  fuse  with  the  main  or  fundamental  tone, 
and  give  it  a  richer  effect.  They  are  called  overtones,  because 
they  overlay  the  fundamental  tone.  The  fundamental  with 
its  overtones  make  a  single  sound,  called  a  simple  clang. 

Overtones  are  responsible  for  our  abiUty  to  distinguish 


CH.  v]  OVERTONES  AND  TBIBRE  05 

between  different  musical  instruments.  In  some  instruments 
one  set  of  overtones  are  more  prominent,  in  others  another 
set.  This  is  why  we  can  readily  distinguish  a  wind  instru- 
ment from  a  stringed  instrument,  even  if  they  play  the  same 
tune.  This  individual  effect  of  each  instrument  is  called  its 
timbre.  The  human  voice  has  a  great  variety  of  overtones, 
and  each  human  voice  has  a  timbre  of  its  own.  A  well-made 
tuning  fork  has  practically  no  overtones;  it  gives  the  nearest 
to  a  pure  tone  of  any  instrument. 

Differences  in  timbre  correspond  roughly  to  the  series  of 
tints  in  colors.  They  give  us  a  variety  of  additional  sensations 
over  and  above  the  pure  tones.  If  we  take  into  account  these 
timbre  differences,  the  number  of  different  sounds  that  we 
hear  is  many  times  greater  than  11,000. 

Difference  Tones.  —  When  two  tones  are  heard  at  the 
same  time  they  combine  in  such  a  way  that  their  identity  is 
partly  lost.  This  combination  effect  is  called  fusion.  In 
tonal  fusion  the  tones  do  not  merge  together  completely; 
with  practice  either  of  the  components  can  be  picked  out 
from  the  total  impression.  Tonal  fusion  is  due  to  a  different 
kind  of  collection  of  nerve  impulses  from  that  which  occurs 
in  sight.  When  different  colors  stimulate  neighboring  parts 
of  the  retina  the  sensations  are  distinct  and  the  only  modifica- 
tion that  occurs  in  the  combination  is  the  contrast  effect. 

When  two  tones  (such  as  C  and  E)  are  sounded  together, 
you  will  be  able  after  practice  to  distinguish  along  with  them 
a  third  tone,  called  the  difference  tone.  Difference  tones  are 
produced  by  the  combination  of  the  two  sound  waves  —  not 
by  a  third  stimulus.  They  arise  in  this  way:  Suppose  you 
start  with  two  tones  almost  alike  —  say,  one  of  256,  the  other 
of  257  vibrations.  Then,  once  every  second  the  two  sound 
waves  will  reinforce  each  other  and  make  a  louder  sound;  and 
once  every  second  the  two  forces  will  be  working  against 
each  other  —  one  pushing  the  particles  forward,  the  othes 
pushing  them  backward  —  so  that  the  result  will  be  a  softer 


99  HEARING  [ch.  v 

sound.  This  loud-and-soft  effect  constitutes  a  beat,  and  the 
number  of  beats  is  always  equal  to  the  difference  between  the 
vibration  rates  of  the  two  tones.  When  a  tuning  fork  of  256 
and  one  of  258  vibrations  are  sounded  together  there  will  be 
two  beats  every  second;  with  forks  of  256  and  266  there  will 
be  ten  beats  every  second,  and  so  on.  As  the  difference  be- 
tween the  two  tones  is  increased  the  beats  increase  in  number, 
till  at  length  they  become  so  rapid  as  to  be  indistinguishable; 
instead  of  hearing  beats  we  hear  a  deep  tone,  which  is  the 
difference  tone.  The  rate  of  a  difference  tone  is  always  equal 
to  the  difference  of  rate  between  the  two  tones  which  are 
sounded  together. 

So  then,  whenever  two  tones  differing  by  more  than  16 
vibrations  are  sounded  together  it  is  possible  to  hear  three 
tones  —  two  primary  and  one  difference  tone;  and  when  three 
tones  are  sounded  together  we  may  hear  six  —  three  primary 
tones  and  the  difference  tone  of  each  pair;  and  so  on.  The 
primary  tones  and  difference  tones  fuse  together  into  one 
complex  impression.  These  complex  sensations  are  called 
compound  clangs.  A  noise  may  be  regarded  as  the  limiting 
case  of  a  compound  clang. 

Difference  tones  help  to  explain  the  fact  that  simple  ratios 
in  tone  inter vak  are  more  pleasing  than  ratios  expressed  in 
large  numbers.  For  if  the  ratio  of  two  tones  is  simple,  the 
difference  tone  will  be  proportional  to  the  primaries:  the  dif- 
ference tone  of  256  and  320  is  64,  which  is  one-quarter  of  256. 
But  if  the  two  tones  are  not  in  simple  ratio  the  difference  tone 
will  make  beats  or  secondary  difference  tones  with  each  tone 
of  the  pair,  and  these  again  will  make  beats  with  the  pri- 
maries. In  other  words,  if  the  ratio  between  the  two  is 
not  simple  the  result  will  be  a  conglomerate  mass  of  jarring 
vibrations  —  an  unpleasant  noise,  instead  of  a  clear-cut  com- 
pound clang. 

Intensity  and  Other  Characteristics.  —  Differences  in  in- 
tensity or  loudness  of  sound  sensations  are  due  to  differences 


CH.  v]  SOUND  INTENSITY  97 

in  the  force  of  the  sound  waves.  The  faintest  audible  sound 
is  produced  by  dropping  a  cork  weighing  1  milHgram  ^  from  a 
height  of  1  mm.,  the  ear  being  91  mm.  distant.  The  upper 
hmit  of  intensity  has  not  been  determined;  loud  sounds  tend 
to  become  more  and  more  painful,  and  in  the  end  produce 
actual  injury  to  the  ear-drum. 

Very  deep  and  very  shrill  sounds  are  usually  not  so  loud  as 
those  in  the  '  middle  range  '  —  that  is,  those  within  the  com- 
pass of  the  human  voice.  Middle-range  sounds  are  also 
easier  to  locate.  A  deep  organ  tone  seems  to  fill  the  air.  A 
shrill  tone,  such  as  the  chirp  of  a  cricket,  is  thin  and  unex- 
tended;  it  is  difficult  to  determine  the  source  unless  we  see  it. 
Sounds  in  the  middle  range  of  pitch  can  usually  be  rather 
definitely  located.  The  two  ears  assist  considerably  in  this 
determination.  Sounds  on  our  right  give  a  louder  effect  in 
the  right  ear  than  in  the  left.  A  sound  in  the  medial  plane 
of  the  body  is  most  difficult  to  locate  correctly.  Often  a 
noise  that  seems  at  first  to  come  from  in  front  is  afterwards 
found  to  be  behind  us. 

Importance  of  Hearing.  —  The  tone  series  in  hearing  corre- 
sponds to  the  series  of  pure  hues  in  sight,  and  the  timbre 
series  to  the  series  of  tints.  There  are  about  11,000  pure 
tones,  as  compared  with  only  about  160  pure  hues,  and  there 
are  far  more  grades  of  timbre  than  grades  of  tint,  so  that 
altogether  we  receive  a  greater  variety  of  simple  sensations 
in  hearing  than  in  sight.''  On  the  other  hand,  visual  sensa- 
tions from  different  points  of  the  retina  do  not  fuse.  They 
are  put  together  into  all  sorts  of  patterns,  corresponding  to 
the  objects  which  stimulate  the  eye;  while  auditory  sensa- 
tions give  one  single  composite  effect  at  any  given  instant; 
so  that  the  eye  furnishes  more  detailed  information  of  the 
world  about  us  than  the  ear. 

'  One  milligram  (mg.)  is  about  15  thousandths  of  a  grain  avoirdupois. 
*  In  spite  of  the  great  number  of  shades,  which  increases  the  variety  of 
our  visual  sensations. 


SMELL 


[CH.  V 


The  sense  of  hearing  is  chiefly  important  in  two  ways:  (1) 
Music  adds  much  to  the  pleasure  of  life.  The  average  human 
being  gets  more  happiness  from  singing,  humming,  and  listen- 
ing to  music  than  from  looking  at  landscapes  and  pictures. 
(2)  Spoken  language  is  received  through  the  ear.  It  is  a 
readier  means  of  communication  among  human  beings  than 
gesture  or  written  language,  which  stimulate  the  eye.  Be- 
cause of  this  advantage,  the  evolution  of  hearing  has  been  a 
powerful  factor  in  promoting  communication  and  social  life 
in  the  human  race  and  in  developing  the  higher  mental 
processes  (ch.  xiii). 

•^  3.  Smell  (Olfaction) 

Receptor  and  Stimulus  for  Smell.  —  The  organ  for  smell  is 
far  simpler  than  either  the  eye  or  the  ear.  In  fact  none  of 
the  other  sense  receptors  begin  to  compare  in  complexity 


Fig.  42,  —  Nasal  Cavity  and  Olfactory  Region 

Vertical  section  of  head,  viewed  from  front,  passing  through  the  rear  part  of  eyebalb.  The 
olfactory  region  lies  mainly  at  the  upper  end  of  the  long  narrow  passages  at  each  side  of  the  cen- 
tral vertical  membrane  (septum)  of  the  nose.    [From  Wenzel.J 


CH.  V 


RECEPTOR  AND  STIMULUS 


09 


with  the  eye  or  the  ear,  except  the  receptor  for  the  static 
sense  (p.  117). 

The  olfactory  receptors  consist  of  a  number  of  spindle- 
shaped  cells,  which  are  embedded  in  the  lining  of  the  nostrils.' 
They  lie  far  back  in  the  nasal  passages.  [Figs.  42,  43.]  Each 
olfactory  spindle  is  connected  with  a  fiber  of  the  olfactory 
nerve. 

The  stimulus  for  smell  consists  of  very  minute  odorous 
particles  which  em- 
anate from  various 
objects  (especially 
organic  matter)  and 
permeate  the  sur- 
rounding air.  They 
sometimes  travel 
great  distances.  In 
blossom-time  we  can 
scent  the  fragrance 
of  a  peach  orchard 
from  afar.  The 
odor  emanations  are  drawn  into  the  nose  in  breathing.  As 
they  pass  through  the  nostrils  some  strike  the  olfactory  cells 
and  stimulate  them.  The  stimuli  include  many  varieties  of 
particles  which  excite  different  kinds  of  nerve  impulses  in  the 
olfactory  nerve.  The  process  of  stimulation  is  apparently 
a  chemical  action.  The  neurons  of  the  olfactory  nerve  start- 
ing at  the  spindles  carry  the  impulses  to  the  olfactory  center 
in  the  brain. 

Odors.  —  Olfactory  sensations  are  called  odors.  Although 
the  receptor  for  smell  is  simple,  a  great  number  of  different 
qualities  can  be  distinguished.  No  complete  list  of  odors 
has  ever  been  made,  and  their  total  number  has  not  yet 
been  estimated.     New  qualities  are  often  discovered  when 

^  The  nose  b  not  a  receptor,  like  the  eye  or  ear;  it  is  part  of  the  organ  for 
breathing. 


Fig.  43.  —  Olfactort  Cells 

Section  of  mucous  membrane  within  the  nose,  showing 
olfactory  cells  (OC)  and  nerve  fibers  (N)  which  connect 
with  them.    SC  =  sup(>orting  cell.     [Based  on  Piersol.) 


100  SMELL  [CH.  V 

we  come  across  a  new  fruit  or  some  new  chemical  com- 
pound. 

The  odors  do  not  form  a  simple  series,  like  the  color  hues 
or  auditory  tones.  They  fall  into  several  groups  or  series, 
and  these  are  mutually  related  through  intermediate  odors. 
Recent  investigation  shows  that  there  are  six  distinct  types 
of  odors:  Fragrant,  ethereal,  foul,  aromatic,  balsamic,  and 
empyreumatic.  [Table  III.]  A  typical  fragrant  odor  is 
heliotropine.  From  pure  fragrance  there  is  a  series  of  odors 
becoming  more  and  more  ethereal,  the  odor  of  geranium  being 
about  midway  between.  There  is  also  a  graded  series  from 
fragrant  to  /omZ,  and  from  fragrant  to  aromatic;  and  so  for 
other  pairs. 

Table  III.  —  Classes  of  Odors 
Class  Examples 

1.  Fragrant  or  flowery  Heliotropine,  Tonka  bean 

2.  Ethereal  or  fruity  Lemon,  oil  of  bergamot 

8.  Foul  or  putrid  Rancid  cheese,  carbon  bisulphide 

4.  Aromatic  or  spicy  Anise,  pepper 

6.  Balsamic  or  resinous  Camphor,  turpentine 

6.  Empyreumatic  or  smoky  Tar,  pyridine 

[After  Henning,  Zsch.  f.  Psychol..  1915,  73,  pp.  240-257.] 

The  relations  of  odors  are  represented  in  the  form  of  a 
prism  [Fig.  44],  because  the  six  types  can  be  arranged  as 
corner  points  of  three  surfaces,  with  cross-series  between  the 
diagonal  corners  of  each.  There  are  cross-series  between  the 
fragrant  and  empyreumatic,  and  between  the  aromatic  and 
foul ;  and  similarly  for  the  diagonals  of  the  other  two  surfaces 
of  the  prism.'  An  interesting  case  is  the  odor  at  the  inter- 
section of  diagonals.  For  example,  the  odor  of  parsley  is 
midway  between  fragrant  and  empyreumatic,  and  it  is  also 
midway  between  foul  and  aromatic.  The  prism  diagram 
means  that  if  you  take  samples  of  every  different  odor  and 

^  The  prism  is  hollow  —  there  are  no  odors  represented  by  points  in  the 
inside. 


CH.  V] 


ODORS 


101 


3.  Foul 


arrange  them  in  this  way,  there  will  be  gradual  changes  of 
odor  as  you  sniff  the  samples  in  regular  order  —  in  no  case 
will  there  be  an  abrupt  change. 

Intensity  differences  in  smell  depend  not  so  much  upon  the 
force  with  which  individual  particles  strike  the  olfactory 
spindles,  as  on  the  density  of  the 
stimuli  —  that  is,  on  the  number 
of  particles  drawn  into  the  nos- 
trils at  a  time.  With  a  uniform 
rate  of  breathing  the  intensity  of 
the  odor  is  greater  according  to 
the  density  of  the  emanation 
from  the  odorous  substance.  Dif- 
ferences in  intensity  may  be 
tested  by  means  of  a  series  of 
bottles  containing  some  odorous 
substance  in  different  degrees  of 
dilution.    The  more  concentrated 

.  Showing  relation  of  the  sis  types  of 

the  solution,    the    more    particles     odora  to  one  another.     (Modified  after 
•11  ,      m  •,  11  Henning  and  Titchener.l 

Will  emanate  from  it,  and  hence 

the  greater  will  be  the  intensity  of  the  sensation. 

Intensity  tests  are  also  made  with  the  olfactometer.  [Fig. 
45.]  This  apparatus  consists  of  two  parallel  tubes,  curved  at 
one  end  for  insertion  in  the  nostrils.  Tubes  lined  with  sub- 
stances containing  odorous  particles  are  drawn  over  the 
straight  end  of  the  olfactometer;  the  intensity  of  the  odor 
varies  with  the  amount  of  exposed  surface  of  odor-bearing 
substance  —  that  is,  with  the  length  of  the  projecting  part 
of  the  odor-tube. 

Either  of  these  apparatus  may  be  used  to  determine  the 
lower  limit  of  intensity.  The  least  observable  intensity 
varies  widely  according  to  the  substance  used;  for  mercaptan 
it  is  about  0.000,000,043  mg.  in  a  liter  of  air.  This  is  one  of 
the  lowest  values :  in  other  words,  the  smell  receptor  is  more 
sensitive  to  mercaptan  than  to  almost  any  other  substance. 


4.Aromdtie  5.  Balsamic 

Fig.  44.  —  Odob  Pbism 


102 


SMELL 


[CH.  V 


Importance  of  Smell.  —  Much  remains  to  round  out  our 
systematic  knowledge  of  smell.  The  reason  for  this  back- 
wardness is  that  smell  plays  a  relatively  small  part  in  human 

life.  Pleasant  odors  are 
sources  of  esthetic  enjoy- 
ment, and  unpleasant 
odors  sometimes  serve  to 
warn  us  of  danger  in  the 
environment.  But  smell 
is  not  especially  impor- 
tant, like  sight,  hearing, 
or  touch,  in  extending  our 
knowledge  of  the  outer 
world.  Man  has  not  the 
capacity  for  fine  discrimi- 
nation in  this  field.  In 
the  dog,  the  deer,  the  ant, 
and  certain  other  species 
the  sense  of  smell  is  much 
more  highly  developed. 
Odors  are  the  dog's  chief 


Fig.  45.  —  Olfactometer 


The  bent  tubes  at  left  are  inserted  in  the  nostrils. 
Tubes  lined  with  some  odorous  substance  are  drawn 
over  straight  part  of  tubes  at  right.  Amount  of 
exposed  surface  is  indicated  on  the  scale.  The  up- 
right screen  conceals  position  of  odor-tubes  from  cluC  in  foUoWlUg  a  trail, 
observer.  ,  i  xi 

where  men  rely  on  the 
sight  of  footprints,  broken  twigs,  and  other  visual  clues. 
With  man,  smell  is  a  luxury  or  an  ornament,  not  an  essen- 
tial part  of  his  life  equipment. 

Historically  this  sense  arose  in  connection  with  the  feeding 
process.  It  is  an  offshoot  of  a  primitive  food  sense,  which  at 
some  point  in  evolution  divided  into  the  two  senses  of  smell 
and  taste.  Like  other  senses,  smell  came  in  the  course  of 
time  to  acquire  new  uses.  The  deer,  for  example,  detects  the 
presence  of  enemies  by  their  odors. 

The  three  distant  senses  —  sight,  hearing,  smell  —  fill  some- 
what the  same  place  in  the  mental  life  of  animals.  So  it 
happens  frequently  that  where  one  of  these  three  senses  be- 


>    ■ 

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^^^ 

^ 

^^t" 

■.•>'  ■  »-^^^^^Bi^HI^BBH 

9^^l 

m 

H 

m 

te 

^K}  'mm  ^H.^sssxr 

^^^W 

^^ 

H^^I^'H) 

"     KiH^i^ 

^^Wm 

^ 

^^^^ 

^  i^B 

B 

i 

w 

f»-fl^ 

n 

1 

Ur. 

|H|H| 

PPH 

H^^^Si 

fi"V| 

^m 

S 

^m 

^H 

^^ 

^sKm 

ii^i 

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w 

Fig.  46.  —  Tongue,  showing  Papilla 

Taste  bulbs  are  located  in  the  circumvnilate  (C)  and  fungiform  (Fu)  papillse.     None 
are  found  in  the  filiform  (Fi)  or  foliate  (Fd).     [From  Wenzel.j 


CH.  \] 


BIPORTANCE  OF  SMELL 


103 


comes  highly  developed  in  a  given  species,  one  of  the  others 
degenerates.  This  is  the  case  with  smell  in  the  human  spe- 
cies. Sight  and  hearing  overshadow  it  so  completely  that 
we  scarcely  ever  rely  upon  it  for  help  in  the  important  affairs 
of  life. 

4.  Taste  (Gustation) 

Receptor  and  Stimulus  for  Taste. —  We  come  now  to  the 
senses  which  are  stimulated  only  by  objects  near  our  body  or 
in  actual  contact  with  it.  These  are  called  contiguous  senses, 
in  distinction  from  the  distant  senses.  Taste  is  the  most 
stay-at-home  of  all  the  external  senses.  The  tastable  sub- 
stance has  to  get  inside  the  mouth  before  it  can  become  a 
stimulus. 

The  receptors  for  taste  are  certain  bodies  shaped  like  bulbs 
or  flasks,  which  are  inserted  in  the  mucous  lining  of  the  tongue 
and  palate.  [Fi^.  46,  47.]  These  bulbs  have  a  small  open- 
ing or  pore  at  the 
neck  end,  which  re- 
ceives the  stimulus; 
the  taste  cells  he  in 
the  walls  of  the  taste 
bulbs.  The  stimuli 
are  always  in  liq- 
uid form;  soUd  sub- 
stances are  tasted 
only  when  dissolved 
by  action  of  the  sa- 
liva. Fibers  from 
three  of  the  cranial 
nerves  connect  with  the  cells  in  the  taste  bulbs  at  various 
parts  of  the  tongue  and  convey  the  impulses  furnished  by 
the  stimuli  to  a  taste  center  in  the  brain. 

Taste  Sensations. —  Tastes  and  odors  are  often  confused. 
We  imagine  that  certain  substances  have  very  pronounced 


EC  TB 


Fig.  47.  —  Taste  Bulbs  and  Taste  Cells 

Section  of  lining  of  papills  of  tongue,  showing  taste  bulbs 
(TB).  with  pore  (P)  at  neck  anH  taste  cells  (TO  forming 
part  of  the  bulb;  EC  =  epithelial  cells.    [Based  on  Piersol.1 


104  TASTE  [CH.  V 

tastes,  which  in  reality  have  no  taste  at  all.  This  is  because 
much  of  the  food  which  we  take  into  the  mouth  consists  of 
odorous  substances.  We  breathe  while  we  are  chewing,  and 
the  odor-particles  are  carried  out  with  our  exhaled  breath 
through  the  nostrils.  Naturally  we  associate  the  resulting 
sensations  with  the  food  in  the  mouth,  and  regard  them  as 
sensations  of  taste.  The  real  nature  of  these  sensations  may 
be  determined  by  holding  the  nose  while  chewing,  so  that  no 
odorous  particle  can  stimulate  the  receptor  for  smell.  Such 
a  test  will  cause  many  surprises.  It  will  be  found  that  an 
onion  and  a  potato  do  not  differ  in  taste  at  all;  their  tremen- 
dous difference  in  odor  has  led  us  to  imagine  that  there  is  a 
difference  in  their  taste  quality  also.  Usually  the  sense- 
impression  which  we  derive  from  food  is  a  mixture  of  various 
sensations  —  chiefly  smell  and  taste,  partly  also  touch  and 
temperature.  This  mixed  sensation  is  called  the  flavor  of 
food.  It  is  by  no  means  easy  to  pick  out  its  various  com- 
ponents. 

The  confusion  between  taste  and  smell  sensations  is  respon- 
sible for  the  prevalent  belief  that  taste  affords  a  great  number 
of  different  qualities.  The  most  careful  examination  indi- 
cates only  four  qualities  in  taste: 

Sweet 

Sour  (or  add) 
1  Saline  j* 

Bitter 

Some  observers  notice  two  other  qualities,  metallic  and 
alkaline;  these  are  probably  combinations  of  taste  qualities. 
The  four  simple  qualities  do  not  form  a  series.  They  bear  no 
special  relation  to  one  another  except  that  sweetness  con- 
trasts to  a  certain  extent  with  the  other  three. 

Intensity  differences  in  taste  may  be  tested  by  means  of 
bottles  containing  solutions  of  some  tastable  substance  in 
varying  degrees  of  concentration.  The  solutions  are  applied 
successively  to  the  tongue  by  means  of  a  brush.    It  is  rather 


CH.  v]  TASTE  SENSATIONS  lOff 

diflScult  to  compare  two  taste  intensities,  because  the  stimuli 
tend  to  persist;  it  requires  some  ingenuity  to  remove  a  taste- 
ful substance  from  the  tongue  quickly  enough  to  compare  it 
accurately  with  the  next  stimulus.  The  least  observable  in- 
tensity of  taste  differs  widely  for  the  four  qualities.   [Table  FV.] 

Table  IV.  —  Least  Obsebvable  Intensity  for  Taste 
Quality  Substance         Dilution  in  Water 


Bitter 

Quinine 

1:390,000 

Saline 

Salt 

1:      2,240 

Sour 

Sulphuric  acid 

1:      2,080 

Sweet 

Sugar 

1:         199 

[From  Sanford,  Exp.  Psychol.,  p.  48,  after  Bailey  and  Nichols.] 

Significance  of  Taste.  —  Pleasant  tastes  or  flavors  add  con- 
siderably to  the  enjoyment  of  food,  and  unpleasant  flavors 
often  enable  us  to  reject  what  is  unpalatable.  On  the  other 
hand,  certain  nutritious  dishes  may  acquire  an  unpleasant 
association  through  taste.  If  you  were  fed  up  with  prunes  as 
a  child,  the  taste  of  prunes  will  be  disagreeable  to  you  in  later 
Ufe.  Most  of  us  have  a  distaste  of  this  sort,  often  a  loathing, 
for  certain  articles  of  food  which  are  by  no  means  harmful  — 
which  in  fact  may  be  very  beneficial.  It  is  also  true  that 
pleasant  tastes  or  flavors  are  sometimes  obtained  from 
unwholesome  foodstuffs.  Savages  and  civilized  men  alike 
are  prone  to  overeat  of  delicious  substances  which  injure  the 
digestive  organs. 

The  information  about  the  outer  world  which  this  sense 
gives  us  is  of  some  value  in  life.  Yet  we  cannot  but  imagine 
that  the  taste  sense  would  have  been  more  useful  if  pleasant 
and  unpleasant  tastes  corresponded  more  closely  to  the 
nutritious  and  harmful.  On  the  whole,  taste  is  probably  the 
least  valuable  of  all  the  senses. 

5—7.  Cutaneous  Senses:  Touch,  Warmth,  Cold 

Cutaneous  Receptors  and  Stimuli.  —  The  outer  surface  of 
the  body  is  susceptible  to  several  kinds  of  stimulation  which 


106  TOUCH,  WARMTH,  COLD  [ch.  v 

are  grouped  together  in  popular  language  under  the  name  of 
'  touch.'  In  reality  there  are  diflferent  receptors  for  the 
various  stimuli,  so  that  we  are  bound  to  treat  the  skin  sensa- 
tions as  forming  several  distinct  senses. 

In  addition  to  the  touch  sense,  there  are  senses  of  warmth 
and  cold.  These  two  are  not  merely  different  qualities  but 
separate  senses,  as  is  shown  by  a  simple  experiment.  Mark 
off  an  area  20  mm.  square  on  some  one's  arm.  Take  a  knit- 
ting needle  which  has  been  chilled  in  ice-cold  water,  and 
explore  this  area  systematically,  marking  in  ink  each  spot 
which  the  observer  reports  as  feeling  *  cold.'  When  a  com- 
plete map  of  the  cold  spots  has  been  made,  explore  the  same 
area  with  a  needle  warmed  in  hot  water,  and  mark  the  warm 
spots  with  a  different-colored  ink.  The  arrangement  of  the 
cold  and  warm  spots  is  found  to  be  very  different. 

Every  spot  on  the  skin  is  stimulated  by  contact  and  gives  a 
touch  sensation.  But  we  find  that  certain  spots  give  also  a 
pressure  sensation  distinct  from  contact.  The  arrangement  of 
pressure  spots  does  not  correspond  to  either  the  warm  or  the 
cold  spots.  [Fig.  48.]  This  indicates  that  the  three  are 
different  senses. 

If  we  examine  the  structure  of  the  skin  with  a  microscope, 
we  find  several  different  kinds  of  corpuscles  embedded  in  it 
and  connected  with  nerve  endings.  The  most  noticeable  of 
these  in  man  are  the  corpuscles  of  Vater-Pacini,  Meissner, 
Krause,  and  Merkel.  [Fig.  49.]  Some  of  these  types  lie  near 
the  surface;  others  lie  deeper  in  the  skin.  It  is  believed  that 
these  several  types  are  receptors  for  different  cutaneous 
senses. 

The  receptors  for  touch,  warmth,  and  cold  are  distributed 
over  the  entire  outer  surface  of  the  body.  There  are  touch 
corpuscles  at  the  roots  of  the  body-hairs;  they  are  found  also 
in  the  eyeball,  tongue,  and  other  special  organs.  Some  of  the 
inner  organs  are  sensitive  to  contact  and  pressure  but  not  to 
temperature  stimuli. 


CH.  V] 


RECEPTORS  AND  STIMULI 


107 


The  stimulus  for  touch  is  the  con- 
tact of  any  substance  with  the  skin. 
The  stimulus  acts  mechanically 
(not  chemically)  on  the  touch  cor- 
puscles. The  warmth  stimuli  are 
heat  waves  that  penetrate  the  skin 
and  act  on  the  receptors  for  the 
warmth  sense;  in  order  to  affect 
these  receptors  the  temperature  of 
the  stimulus  must  be  somewhat 
higher  than  the  temperature  of  the 
skin.  The  cold  receptors  are  af- 
fected by  stimuli  that  are  colder 
than  the  skin.  The  cold  receptors 
lie  nearer  the  surface  than  the 
warmth  receptors  and  are  more 
readily  stimulated. 

Cutaneous  Sensations.  —  Each 
of  the  two  temperature  senses  has 
one  characteristic  quality,  called 
warmth  and  cold  respectively.  When 
the  warmth  and  cold  receptors  are 
stimulated  together  the  result  is  a 
sensation  known  as  heat  sensation. 

The  sense  of  touch  has  two  ele- 
mentary qualities,  contact  and  jyres- 
sure;  under  special  conditions  of 
stimulation  touch  gives  rise  to  cer- 
tain other  quality  effects.  We 
distinguish  between  sensations  of 
roughness,  smoothness,  moving  con- 
tact, moisture,  and  stickiness.  The 
sensations  of  tingling  and  itching 
appear  to  be  touch  qualities;  but 
they  are  caused  by  stimuli  within 


Fig.  48.  —  Pressure  and 
Temperature  Spots 

Map  of  palm  of  left  band,  showing 
relative  distribution  of  sensitivity  to 
pressure  (A),  warmth  (B),  and  cold 
(C).  Same  area  is  represented  in  all 
three  cases.  In  A  the  regions  marked 
black  are  relatively  imemitive  to 
pressure.  In  B  and  C  the  areas 
most  tentitite  (to  warmth  and  cold 
respectively)  are  marked  in  black, 
less  sensitive  in  lighter  shading,  etc. 
[From  Schaefer,  after  Goldscheider.l 


108 


TOUCH,  WARMTH,  COLD 


[CH.  V 


the  body  and  are  possibly  organic  sensations.  The  peculiar 
sensation  known  as  tickle  differs  strikingly  from  most  sensa- 
tions, in  that  a  very  faint  stimulus  produces  a  very  intense 
sensation.    The  tickle  sensation  is  probably  due  to  a  definite 


Fia.  49.  —  Cutaneous  Receptobs 

A.  Vater-Pacini  corpuscle. 
I  B.  Transverse  section  of  same. 

'  C.  Meissner  corpuscle. 

D.  Merkel  cells  in  interpapillary  epithelium. 

E.  Krause  end-bulbs  from  human  conjunctiva. 

F.  Free  nerve  endings  in  epidermis  of  rabbit. 
N  =  nerve  fibers. 

touch  stimulus  applied  to  a  very  small  area.  The  other 
special  touch  qualities  are  due  to  spatial  and  temporal  varia- 
tions of  the  stimulus. 

Differences  of  intensity  may  be  examined  in  touch,  warmth, 
and  cold  by  methods  similar  to  those  used  in  the  higher 
senses.    The  least  observable  intensity  in  touch  is  stated  to  be 


CH.  v]  CUTANEOUS  SENSATIONS  109 

the  contact  of  a  cork  weight  of  2  mg.  on  the  tip  of  the  finger. 
For  the  temperature  senses  the  least  observable  sensation  is 
produced  by  a  stimulus  about  one-eighth  degree  warmer  or 
colder  than  the  temperature  of  the  skin. 

Importance  of  the  Skin  Senses.  —  While  the  cutaneous 
sensations  furnish  no  great  variety  of  quahty,  the  fact  that 
their  receptors  are  spread  over  the  entire  body  gives  them 
great  importance  in  life.  Touch  sensations  inform  us  of  the 
location  of  things  which  press  against  the  skin.  They  help 
us  considerably  in  acquiring  knowledge  of  the  shape  and  size 
of  objects,  and  in  perceiving  motion  and  other  space  rela- 
tions (ch.  vii). 

Warmth  and  cold  are  far  less  significant  than  touch.  They 
rarely  occur  apart  from  touch  sensations,  and  usually  com- 
bine with  these,  just  as  taste  and  smell  sensations  combine 
together.  The  information  which  the  temperature  senses 
give  is  useful  so  far  as  it  goes;  these  senses  are  undoubtedly 
more  important  for  life  than  taste.  It  is  interesting  to  notice 
that  warmth  (and  to  a  lesser  degree  cold)  is  in  a  rudimentary 
way  a  distant  sense.  We  feel  the  warmth  of  a  glowing  stove 
at  some  distance,  and  we  can  sense  the  cold  of  ice  before  the 
hand  quite  touches  it. 

8.  Organic  Senses  (Ccenesthesia,  Visceral  Senses) 

The  Systemic  Senses.  —  We  have  examined  the  *  five 
senses  '  recognized  by  popular  tradition,  and  in  doing  so  we 
have  discovered  two  more  —  warmth  and  cold  —  which  were 
improperly  identified  with  touch.  All  these  seven  senses  are 
stimulated  by  external  objects  and  forces.  They  give  us 
information  concerning  situations  and  occurrences  outside 
our  own  body. 

There  are  also  two  senses  which  inform  us  of  conditions 
within  the  body  and  of  what  is  taking  place  there:  (1)  The 
organic  senses  report  the  general  condition  and  workings  of 
our  organs  of  digestion  and  other  internal  organs.     (2)  The 


110  ORGANIC  SENSES  [ch.  v 

pain  sense  reports  injuries  which  happen  to  our  body  and 
which  may  be  due  to  either  internal  or  external  causes.  The 
two,  taken  together,  are  called  systemic  senses,  because 
they  report  events  that  occur  in  our  bodily  system. 

Information  about  our  bodily  processes  is  quite  as  impor- 
tant a  factor  in  life  as  knowledge  of  the  outer  world.  The 
organic  and  pain  senses  do  not  deserve  to  be  ignored  as  they 
used  to  be.  The  student  of  psychology  who  insists  on  recog- 
nizing only  the  traditional  five  senses  ought  to  be  inflicted 
with  a  jmnping  toothache  till  he  admits  at  least  a  sense  of 
pain. 

Organic  Sensations.  —  The  organic  senses  are  extremely 
diflficult  to  investigate,  because  their  receptors  lie  buried  so 
deep  within  the  body  that  they  are  generally  inaccessible  to 
examination.  Our  knowledge  of  them  is  very  imperfect. 
Not  only  is  it  difficult  to  determine  exactly  the  number  of 
different  sensation-quahties  that  they  furnish,  but  it  is 
uncertain  how  many  of  them  have  different  kinds  of  recep- 
tors and  are  really  separate  senses. 

There  are  at  least  four  important  sorts  of  organic  sensa- 
tions: (1)  digestive  sensations,  (2)  vascular  and  respiratory 
sensations,  (3)  generative  sensations,  and  (4)  feeling  tone. 
The  first  three  are  connected  with  the  operation  of  the  great 
systems  of  life  functions  after  which  they  are  named.  Feel- 
ing or  hedonic  tone  is  apparently  due  to  metabolic  ^  conditions 
within  the  body. 

Among  our  digestive  sensations  the  most  easily  distinguished 
are  hunger  and  thirst.  Under  careful  examination  the  sensa- 
tion of  hunger  proves  to  be  a  complex  affair.  It  includes 
hunger  pangs,  due  to  muscular  contractions  in  the  stomach; 
appetite  or  craving  for  food,  which  sometimes  occurs  even 
when  the  stomach  is  filled;  general  discomfort  due  to  starva- 
tion and  depletion  of  the  tissues.    A  distinct  sensation  quahty 

^  Metabolism  includes  various  chemical  changes,  especially  the  destruc- 
tion and  restoration  of  tissue. 


CH.  v]     VARIETY  OF  ORGANIC  SENSATIONS     111 

accompanies  the  satisfaction  of  hunger.  Thirst  is  probably 
due  to  drying  of  the  mucous  membrane  in  the  mouth  and 
throat.  Another  digestive  sensation  is  nausea,  which  has  a 
very  pronounced  quahty.  There  is  also  a  special  sensation 
in  the  digestive  tracts  due  to  distension  of  the  stomach  and 
other  cavities.  Less  definite  sensations  accompany  the  later 
digestive  processes  in  the  intestines,  bladder,  etc.  There  are 
also  sensations  connected  with  urination  and  defecation. 
Associated  with  the  digestive  sensations  is  a  sensation  local- 
ized in  the  abdominal  region,  which  is  stimulated  under 
emotional  conditions  of  fright,  anger,  affection,  etc.  Al- 
though the  various  sensations  just  described  are  all  associated 
with  the  digestive  processes,  they  are  due  to  distinct  stimuH 
and  in  some  cases  probably  involve  different  kinds  of  recej>- 
tors. 

The  vascular  and  respiratory  sensations  are  less  varied  and 
much  more  obscure.  The  circulation  of  the  blood  is  accom- 
panied at  times  by  distinctive  sensations  such  as  flushing, 
heart  quavers,  throbbing,  and  tingling  of  the  blood.  Breath- 
ing is  often  accompanied  by  an  unnamed  sensation  of  *  expan- 
sion,' or  its  opposite,  *  stuffiness.'  Sensations  from  circula- 
tion and  respiration  are  present  in  states  of  trepidation, 
anxiety,  and  panic.  But  for  the  most  part  the  autonomic 
bodily  processes  go  on  without  any  sensations  except  a 
feeling  tone. 

The  reproductive  organs  furnish  a  number  of  distinctive 
generative  sensations.  These  include  the  sensations  of  sexual 
craving,  sexual  excitement,  orgasmic  sensations,  and  sexual 
satisfaction.  The  generative  system  also  contributes  to  the 
general  feehng  tone  of  the  body. 

Feeling  tone  is  a  vague  sensation  which  often  accompanies 
other  sensations.  It  includes  two  opposite  qualities,  pleas- 
antness and  unpleasantness.  It  probably  has  no  special 
receptor  of  its  own,  but  is  due  to  certain  characteristics  com- 
mon to  all  the  stimuli  which  act  upon  the  organic  receptors. 


112  ORGANIC  SENSES  [ch.  v 

The  chemical  (metabolic)  changes  which  take  place  in  the 
body  are  of  two  opposite  sorts  —  constructive  and  destruc- 
tive processes.  New  cells  are  built  up  and  the  wastage  of 
cells  is  restored;  this  process  is  called  anabolism.  Cells  are 
destroyed  or  impaired  by  use,  giving  the  opposite  process, 
catabolism.  The  organic  sense  receptors  are  affected  by 
these  two  kinds  of  life  processes  as  well  as  by  their  own 
special  stimuli.  That  is,  organic  stimuli,  whatever  else  they 
may  be,  are  either  anabolic  or  catabolic;  so  that  any  organic 
sensation,  besides  having  its  own  quality  (hunger,  heart 
throb,  craving,  and  the  like),  has  also  a.  feeling  tone,  which  is 
pleasant  if  the  stimulation  is  anabolic  and  unpleasant  if  it  is 
catabolic.  Draw  a  series  of  slow,  deep  breaths  and  you  will 
notice  a  growing  feeling  of  pleasantness  in  the  region  of  the 
lungs.  Notice  the  gradual  onset  of  unpleasantness  which 
accompanies  nausea.  In  each  case  the  feeling  tone  is  diflFeiv 
ent  from  the  special  quality  of  the  sensation. 

The  external  sensations  have  a  certain  degree  of  feeling 
tone  also.  Many  sounds  and  tastes  are  noticeably  agreeable 
or  disagreeable.  A  man  will  almost  sell  his  soul  for  a  lus- 
cious peach,  and  sometimes  he  is  quite  ready  to  murder  an 
ear-racking  organ-grinder.  But  in  the  external  senses  the 
special  quality  of  the  sensation  is  so  pronounced  that  the 
feeling  factor  is  usually  of  secondary  importance.  On  the 
other  hand,  most  of  our  digestive  and  other  organic  sensa- 
tions are  observed  chiefly  as  a  feeling  tone  of  pleasantness  or 
unpleasantness;  their  own  special  qualities  are  subordinate. 

Besides  the  feeling  tone  connected  with  various  senses, 
we  experience  a.  feeling  of  general  sensihiliiy,  or  general  feeling 
tone,  in  the  body  as  a  whole.  This  general  feeling  varies  from 
time  to  time.  It  gives  sensations  of  well-being,  vigor,  buoy- 
ancy, repletion,  drowsiness,  discomfort,  fatigue,  weakness, 
and  the  like.  Our  general  feeling  tone  at  any  time  is  a  highly 
important  factor  in  our  mental  life.  The  dyspeptic  and  the 
athlete  live  in  two  very  different  worlds,  even  though  they 


CH.  v]     VARIETY  OF  ORGANIC  SENSATIONS       113 

room  together.  Our  actions  are  not  merely  responses  to  the 
'  midst '  in  which  we  are  placed;  they  reflect  our  own  organic 
condition  as  well.  We  shall  notice  this  especially  when  we 
examine  emotion  and  emotional  attitudes  (chs.  ix,  xv). 

9.  Pain  (Algesthesia) 

Pain  Sensations. —  The  pain  sense  is  like  the  organic 
senses  in  that  it  gives  us  information  concerning  the  state 
of  our  own  bodily  tissues  and  organs.  But  it  is  an  independ- 
ent sense;  its  receptors  are  different  and  it  gives  a  quaUty 
of  sensation  very  different  from  the  organic  or  any  other 
sense. 

The  pain  nerves  form  an  exception  to  sensory  nerves  gen- 
erally, in  that  they  are  not  provided  with  any  special  recep- 
tors. Their  endings  in  the  skin  are  unattached  and  are 
called  free  nerve  endings.  [See  Fig.  49  F.]  One  might  say 
that  they  keep  open  house  for  any  stray  stimuU  that  are 
wandering  about  in  the  body.  This  is  true  in  a  way,  but  it 
needs  qualification.  There  are  no  stray  stimuli  in  the  body, 
except  the  overflow  of  very  intense  stimuU  which  are  too 
powerful  for  their  proper  receptors  to  manage.  Very  bright 
light,  very  intense  heat,  give  more  energy  than  the  receptor 
for  sight  or  warmth  can  absorb;  the  surplus  energy  spreads 
destruction  through  the  neighboring  tissues.  The  free  end- 
ings of  the  pain  nerves  take  up  these  vagabond  stimuU  and 
the  resulting  nerve  impulses  travel  up  to  special  pain  centers 
in  the  brain. 

Pain  sensations  have  a  distinctive  quaUty  of  their  own; 
pain  is  pain,  whatever  its  source.  But  there  are  many  sorts 
of  pain,  each  of  which  bears  the  mark  of  its  origin.  We  dis- 
tinguish between  scratches,  pricks,  stings,  and  sores  (touch) ; 
bums  (temperature);  stomach  pains,  nausea,  intestinal 
pains  (organic);  bruises  and  muscular  soreness  (muscle 
sense).  Certain  eye  pains  are  tactile;  others  are  due  to  strain 
of  the  eye  muscles  (muscle  sense);  occasionally  eye  pain  is 


114  PAIN  [CH.  V 

due  to  intense  light.  Toothache  is  due  to  stimulation  ot 
certain  nerves  which  originate  in  the  teeth.  Shooting 
neuralgic  pains  are  apparently  due  to  internal  stimuli  which 
affect  the  nerves  at  some  point  in  their  course. 

There  is  always  a  marked  feeling  tone  of  unpleasantness  in 
the  pain  sensation.  The  fact  that  pain  stimuli  are  destructive 
to  the  bodily  tissues  (catabolic)  would  account  for  this. 
The  connection  between  the  pain  quality  and  the  unpleasant- 
ness quality  is  so  universal  that  we  find  difficulty  in  dis- 
tinguishing them.  It  is  much  like  the  confusion  between 
tastes  and  odors,  except  that  in  the  latter  case  we  can  readily 
bring  out  the  distinction  by  holding  the  nostrils  closed.  The 
discrimination  between  pain  sensation  and  unpleasant  feeling 
is  not  so  easy.  It  requires  considerable  practice  in  observing 
our  sensations  carefully  before  we  can  say,  "  This  sensation  is 
unpleasant,  but  it  is  not  a  pain." 

However  disagreeable  the  pain  sensations  may  be,  the 
sense  itself  is  useful.  It  serves  to  warn  us  of  dangers,  both 
outside  and  inside  the  body;  it  often  enables  us  to  avoid  or 
remedy  harmful  situations.  In  the  course  of  animal  evolu- 
tion an  elaborate  system  for  receiving  pain  impressions  has 
been  built  up.  In  the  higher  species  the  pain  sense  is  an 
important  factor  in  life.  Far  from  making  the  responses  of 
dogs  and  other  animals  less  suitable  to  the  general  situation, 
pain  sensations  usually  help  the  creature  to  do  the  best  thing 
in  the  circumstances.  The  same  is  true  of  man.  It  is  a 
mistaken  psychological  attitude  to  regard  pain  as  an  evil  or 
mental  error.  Pain  is  part  of  our  equipment  for  meeting  the 
situations  that  confront  us  in  life.  It  is  an  important  factor 
in  adjusting  our  behavior  to  unfavorable  conditions  in  the 
environment. 

10.  Muscle  Sense  (Kinesthesia,  Kinesthetic  Sense) 

The  Motor  Senses.  —  We  have  examined  the  two  great 
groups  of  senses:  those  which  give  information  concerning 


CH.  v]  THE  MOTOR  SENSES  115 

external  objects,  and  those  which  report  conditions  vnthin  our 
own  body.  We  now  come  to  a  third  group :  the  senses  which 
give  information  regarding  our  bodily  movements  and  which 
indicate  the  position  of  our  body  in  space  and  the  relative 
position  of  its  various  members.  For  want  of  a  better  term 
this  group  is  called  the  mot&r  senses,  although  they  indicate 
position  as  well  as  movement.  The  motor  senses  include  (1) 
the  kinesthetic  sense  or  senses,  usually  known  as  the  muscle 
sense,  and  (2)  the  static  or  equilibrium  sense. 

Muscle  Sensations.  —  Kinesthetic  or  muscle  sensations  are 
obtained  through  sensory  nerves  which  start  in  the  muscles, 
tendons,  and  joints.  These  nerves  are  provided  with  special 
receptors  which  are  stimulated  by  contractions  of  the  volun- 
tary (striate)  muscles.  The  muscle  sensations  may  be  ob- 
served by  moving  the  finger,  elbow,  knee,  eyelid,  eyeball,  or 
tongue,  and  noticing  how  the  movement  feels;  the  sensation 
is  quite  different  in  quality  from  the  sensation  of  contact  or 
pressure.  In  certain  diseases  the  patient  is  unable  to  feel 
pressure,  but  has  distinct  sensations  of  movement;  in  other 
cases  the  opposite  is  true.^  This  establishes  the  existence  of 
*  kinesthesia  '  as  a  separate  sense  or  senses.  It  has  not  been 
determined  whether  the  tendons  and  joints  yield  different 
kinds  of  sensations  from  the  muscles.  The  term  muscle  sense 
is  commonly  applied  to  the  whole  group  of  kinesthetic  sensa- 
tions. 

These  sensations  give  information  not  merely  of  bodily 
movements,  but  of  the  position  of  our  members  in  space,  of 
how  they  are  bent,  etc.  When  a  member  is  held  rigid  in  any 
position,  each  of  the  antagonistic  muscles  is  subject  to  a 
certain  amount  of  contraction;  the  two  resulting  sensations 
taken  together  indicate  the  relative  amount  of  muscular 
contraction  and  hence  the  position  of  the  member.  This  may 
be  observed  if  you  close  your  eyes  and  hold  your  bare  arm  in 

^  If  you  wake  up  at  night  with  your  arm  numb,  try  to  move  it,  and  then 
touch  it.    Is  it  the  muscle  sense  that  is  benumbed,  or  touch? 


116  MUSCLE  SENSE  [ch.  v 

some  position  where  it  does  not  touch  the  body,  or  if  you  twist 
your  neck  to  the  right  or  left  and  keep  it  in  this  position;  the 
muscle  sensations  tell  you  what  its  position  is. 

Muscle  sensations  are  usually  reinforced  by  touch  sensa- 
tions, such  as  the  scraping  of  the  clothes  against  the  skin,  and 
by  indications  from  other  external  senses.  When  the  eyes 
are  turned  from  side  to  side,  the  motion  of  the  whole  field  of 
objects  across  the  retina  brings  about  a  general  change  of 
visual  sensations;  in  walking  we  have  a  visual  picture  of  the 
moving  scene.  These  auxiliary  motor  indications  from  the 
external  senses  (touch,  sight,  hearing)  are  not  really  kines- 
thetic sensations,  but  they  assist  materially  in  the  perception 
of  our  posture  and  movements;  they  may  be  termed  second- 
ary motor  sensations. 

There  are  few  differences  of  quality  in  the  muscle  sense. 
When  we  are  actively  pushing  or  lifting  a  heavy  object,  we 
obtain  a  sensation  called  effort;  when  a  member  is  resisting 
external  pressure  there  is  a  sensation  of  strain.  These  sensa- 
tions are  assigned  to  the  tendons.  When  the  muscles  have 
been  active  for  a  long  time  there  arises  a  sensation  of  muscu- 
lar/a^tgrwe;  this  is  possibly  a  form  of  feeling  tone. 

The  intensity  differences  of  muscle  sensations  are  very  pro- 
nounced and  are  finely  discriminated.  A  slight  movement  of 
the  finger  or  arm  is  readily  observed;  the  movements  of  our 
limbs  are  regulated  very  accurately  by  means  of  these  indica- 
tions. This  may  be  easily  tested  by  observing  how  many 
different  positions  of  one  of  your  fingers  you  can  discriminate 
when  your  eyes  are  closed.  The  least  observable  difference  of 
position  for  the  middle  finger  is  found  to  be  1°. 

The  muscle  sense  not  only  serves  to  inform  us  of  our  various 
postures  and  movements,  but  it  also  gives  information  regard- 
ing the  weight  of  external  objects.  If  we  start  to  lift  a  heavy 
suitcase  or  push  a  piano,  the  resistance  which  it  offers  checks 
the  speed  of  our  muscular  contraction;  the  intensity  of  the 
muscle  sensation  is  greater  than  when  we  merely  raise  the  arm. 


CH.  Vl 

y 


STATIC  RECEPTOR 


11.  Static  Sense  (Equilibrium  Sense) 


117 


Static  Receptor  and  Sensations.  —  The  sialic  sense  is 
another  source  of  information  concerning  the  position  and 
movements  of  our 
body.  It  has  noth- 
ing to  do  with  the 
muscles  and  is  en- 
tirely distinct  from 
the  muscle  sense, 
though  the  two 
work  together.  The 
static  receptor  is  a 
complicated  struc- 
ture in  the  inner 
ear,  consisting  of 
the  semicircular  ca- 
nals and  sacs.  The 
canals  are  three  in 
number,  and  are 
placed  at  right  an- 
gles to  one  another 
in  three  different 
planes.  [Fig,  50; 
cf.  Figs.  36,  37.] 
They  are  bony  in 
substance,  and  in 
shape  resemble  a 
horseshoe.  The  ca- 
nals are  situated  in 
the  labyrinth  of  the 
ear,  lying  slightly 
above  and  to  the 
rear  of  the  cochlea. 
endolymph.     Receptor  cells  with  long  projecting  hairs  line 


Fig.  50.  —  Semicihculak  Canals  aot)  Sacs 

Section  through  vestibule  of  left  eur.  (Compare  Fig.  87 
for  right  ear.)  Canals  are  shown  above,  the  sacs  in  middle, 
beginning  of  cochlea  below.  A  =  superior  canal;  B  =  pos- 
terior canal;  C  =  horizontal  canal;  D,  E,  F,  =  ampullse  of 
three  canab;  G  =  utricle;  H  =  saccule;  I  =  oval  window; 
3  =  beginning  of  scala  vestibuli;  K  =  cochlear  duct;  L  = 
scala  tympani,  ending  in  round  window  beneath.  [From 
Wenzel.J 

Each  canal  is  filled  with  a  liquid  called 


118  STATIC  SENSE  (en.  v 

the  walls  of  the  canals.  The  two  sacs,  the  viricle  and  saccule, 
are  rounded  protuberances  situated  in  the  vestibule  near  the 
canals.  They  contain  minute  crystals  called  otoliths.  The 
canals  open  into  the  utricle;  at  the  base  they  enlarge  and  form 
the  ampullce.     The  saccule  lies  just  below  the  utricle. 

The  stimuli  for  static  sensations  are  the  flow  or  pressure  of 
the  endolymph  inside  the  canals,  due  to  changes  in  the  posi- 
tion of  the  head.  The  otoliths  in  the  sacs  are  also  affected  by 
changes  in  the  endolymph.  The  relation  between  the  canals 
and  the  sacs  is  not  clear,  but  it  is  probable  that  the  canals 
give  us  information  of  motion  and  rotation,  while  the  sacs 
indicate  the  position  of  the  head  in  relation  to  gravity. 

Since  the  canals  lie  in  three  different  planes,  any  angular 
change  whatsoever  in  the  position  of  the  head  involves  rota- 
tion of  at  least  one  canal.  When  the  head  is  turned  horizon- 
tally to  the  right,  inertia  causes  the  liquid  in  the  horizontal 
canal  to  circulate  toward  the  left;  when  we  turn  the  head 
to  the  left  the  direction  of  circulation  is  reversed.  K  the 
whole  head  is  moved  forward,  backward,  or  to  one  side,  as  in 
walking,  the  pressure  at  both  ends  of  some  canal  is  increased 
or  diminished.  These  changes  in  the  endolymph  stimulate 
the  sensitive  projecting  hairs  and  this  excites  the  neurons 
of  one  branch  of  the  eighth  cranial  nerve  —  the  same  nerve 
whose  main  branch  is  used  for  hearing;  the  nerve  impulses 
are  carried  to  the  static  center  of  the  brain. 

The  canals  were  formerly  supposed  to  be  connected  with 
the  sense  of  hearing.  But  it  is  found  that  when  a  pigeon's 
canals  are  removed  the  bird  is  imable  to  maintain  his  balance 
or  regulate  his  flight.  Tracing  back  the  evolution  of  the  two 
organs  in  the  animal  scale,  it  is  found  that  the  static  organ 
arose  before  there  was  any  sense  of  hearing;  curious  though  it 
may  seem,  hearing  is  an  outgrowth  or  offshoot  of  the  static 
sense.  In  man  and  other  high  species  hearing  has  developed 
much  further  than  the  static  sense  and  has  far  outstripped  it 
in  importance. 

The  static  sense  gives  sensations  of  position  and  sensations 


CH.  v]  RECEPTOR  AND  SENSATIONS  lift 

of  motion.  In  both  cases  the  static  sensation  is  so  closely 
bound  up  with  muscle  sensations  and  other  motor  informa- 
tion that  it  is  difficult  to  distinguish  its  own  particular  qual- 
ity. The  sensation  of  motion  apparently  differs  in  quality 
from  the  sensation  of  position.  The  sensations  from  the 
three  canals  may  differ  sUghtly  in  quality  also.  Nausea  is 
an  organic  sensation  due  to  some  connection  between  the 
digestive  organs  and  the  static  nerves.  Dizziness  is,  in  part 
at  least,  due  to  eye  movement. 

The  differences  of  intensity  in  static  sensations  may  be 
observed  by  lying  flat  upon  a  rotation  table,  with  eyes  closed, 
while  the  table  is  turned  at  various  rates  of  speed.  The  least 
observable  motion  is  a  rate  of  about  2°  per  second,  starting 
from  a  standstill.  The  stimulus  for  static  sensation  is  the 
acceleration  of  motion,  not  its  velocity.  If  we  are  rotated  on 
the  table  at  a  uniform  rate,  the  sensation  gradually  dies  away; 
then  if  we  twist  the  head  in  any  direction  the  sensation  im- 
mediately starts  up  again. 

Static  sensations,  muscle  sensations,  and  the  perception  of 
movements  through  sight  and  other  external  senses  combine 
to  give  us  information  of  our  bodily  postures  and  movements. 
This  mass  of  motor  information  is  the  basis  of  our  motor 
adjustments  and  plays  an  important  part  in  the  formation  of 
our  motor  habits. 

Significance  of  Sensation  in  Mental  Life.  —  It  cannot  be 
too  strongly  impressed  upon  the  student  of  psychology  that 
all  eleven  senses  must  be  reckoned  with.  Of  the  five  tradi- 
tional senses,  taste  and  smell  are  far  less  important  in  life 
than  the  two  motor  senses  and  pain.  It  is  especially  useful 
to  keep  in  mind  the  three  great  groups  of  senses  —  external, 
systemic,  and  motor}  These  three  types  of  sensation  bear 
essentially  different  relations  to  mental  life.  They  are  the 
basis  of  three  different  sorts  of  mental  activity. 

(1)  The  external  senses  furnish  information  which  leads  to 
perception,  remembering,  and  thinking;  the  sensations  from 
1  See  Table  1,  p.  58. 


120  THE  SENSES  [ch.  v 

these  seven  senses  make  up  our  cognitive  experiences,  or 
intellect  —  the  knowledge  side  of  our  mental  Hfe.  (2)  The 
systemic  senses  furnish  information  concerning  our  internal 
organic  processes  and  bodily  condition;  they  are  the  source 
of  our  affective  experiences  —  our  feelings.  (3)  The  motor 
senses  furnish  information  as  to  the  position  of  the  various 
parts  and  members  of  our  body  in  space,  and  the  direction  and 
rate  of  our  movements;  they  are  the  basis  of  our  active 
experiences  —  our  ivill. 

The  separate  sensations  are  not  experiences;  they  are  the 
elementary  bits  of  information  which  combine  to  make  up  our 
experiences.  Any  conscious  experience  —  perceiving  a  land' 
scape,  the  feeling  of  happiness,  the  sense  of  making  a  sweeping 
arm-movement  —  is  composed  of  a  number  of  separate  sen- 
sations which  are  combined  together  by  the  collecting  of  sep- 
arate nerve  impulses  in  the  brain  centers.  Our  various  ex- 
periences, taken  together,  make  up  our  conscious  mental  life. 

Practical  Exercises: 

22.  Listen  for  difference  tones  and  overtones  on  the  piano  (or  some  other 
musical  instjjument)  and  describe  the  experience. 

23.  Observe  the  sensations  of  taste  from  various  common  foods  while 
holding  the  nose,  and  compare  with  the  usual  sensations. 

24.  Make  a  map  of  warmth  and  cold  spots  as  described  on  page  109. 

25.  Compare  three  different  sorts  of  systemic  sensations,  e.g.,  hunger, 
general  bodily  fatigue,  toothache. 

26.  Observe  your  muscle  sensations  (a)  in  bending  the  elbow  and  fingers, 
and  (6)  in  lifting  a  weight.  Compare  these  with  the  accompanying 
touch  and  pressure  sensations. 

27.  Test  your  static  sensations  on  a  rotation  table  or  in  a  swivel  chair. 
Spin  on  your  heel  (a)  with  head  erect,  (b)  with  head  inclined  to  right, 
left,  or  forward;  observe  the  resulting  sensations.  Look  in  a  mirror 
on  a  moving  train,  shutting  out  direct  sight  of  the  landscape;  observe 
especially  your  sensations  when  the  train  starts  or  stops,  and  when 
it  goes  round  a  curve.    Report  the  results  of  these  observations. 

References: 

On  the  receptors:  Ladd  and  Wood  worth.  Physiological  Psychology,  Part  I, 
ch.  8. 

On  sensations:  E.  A.  Schaeffer,  Textbook  of  Physiology,  articles  'Cutane- 
ous Sensations,'  'Muscular  Sense,'  'The  Ear,'  'Sense  of  Taste,'  'Sense 
of  Smell';  M.  Greenwood,  Physiology  of  the  Special  Senses,  chs.  2-9. 


CHAPTER  VI 

CONSCIOUS  LIFE 

Review. — This  is  a  good  place  to  stop  and  glance  back  over 
the  ground  so  far  covered.  We  started  with  the  notion  of 
psychology  as  the  science  which  investigates  the  responses  of 
living  creatures  to  the  stimuli  that  affect  them.  It  includes 
the  study  of  the  entire  chain  of  events  beginning  with  stimu- 
lation and  ending  with  responsive  activity.  These  processes 
are  carried  out  by  means  of  the  nervous  system  and  the  recep- 
tors and  effectors  which  Ue  at  either  end  of  the  nervous  arc. 
The  whole  series  of  events  make  up  our  mental  life. 

Any  single  episode  in  our  mental  life  may  be  divided  into 
three  successive  stages:  (1)  We  receive  piecemeal  impressions 
from  the  outer  world  or  from  our  own  body.  (2)  We  put  these 
detached  pieces  of  information  together  and  prepare  to  re- 
spond in  an  orderly  and  appropriate  way.  (3)  We  send  out 
nerve  impulses  to  the  muscles  and  glands,  which  thereupon 
perform  the  proper  movements  or  reactions.^  These  three 
parts  of  the  process  are  called  stimidaiion  (or  reception)  ^  ad- 
justment (or  integration),  and  response. 

The  first  stage,  receiving  the  separate  bits  of  material 
(sensations),  was  examined  in  the  two  preceding  chapters. 
The  senses  are  the  means  by  which  all  our  impressions  are 
originally  obtained.  (There  are  also  some  secondary  impres- 
sions, memories,  which  are  only  indirectly  due  to  the  senses.)^ 
The  sense  organs  or  receptors  are  stimulated  by  light  waves, 
sound  waves,  pressure,  and  other  physical  forces,  and  the 

^  This  sounds  somewhat  mechanical  and  artificial,  because  it  attempts 
to  describe  moving,  flowing  events  in  a  piecemeal  way.  If  you  examine  any 
one  of  the  pictures  of  a  galloping  horse  which  enter  into  a  motion  picture 
scene,  the  horse's  position  appears  ridiculous  —  each  momentary  attitud« 
is  very  different  from  your  total  impression  of  galloping. 


122  CONSCIOUS  LIFE  [ch.  ti 

sensory  nerves  conduct  the  resulting  nerve  impulse  to  a 
center  —  in  most  cases  to  a  brain  center.  In  this  way  we 
receive  sensations. 

Sensations  would  be  detached,  piecemeal  experiences,  if 
the  sensory  impulses  which  cause  them  were  not  collected  and 
integrated  in  the  brain  centers.  This  is  the  second  stage  of 
the  mental  process.  In  the  next  few  chapters  we  shall  see 
how  the  separate  elementary  sensations  are  put  together  so  as 
to  make  actual  conscious  experiences.^  Perceptions,  memo- 
ries, emotions,  thoughts,  and  other  experiences  are  such  inte- 
grations; they  are  due  to  the  orderly  combination  of  separate 
sensations,  and  to  various  changes  which  take  place  in  con- 
nection with  the  combining  process.  We  shall  examine  these 
different  sorts  of  experience  in  turn.  But  they  will  be  easier 
to  understand  if  we  explain  first  of  all  what  is  meant  by  con- 
sciousness and  how  our  conscious  life  is  related  to  the  working 
of  our  brain. 

Consciousness  and  Subconsciousness.  —  Consciousness  is 
one  of  those  notions  that  are  perfectly  plain  to  everyone,  and 
yet  are  not  easy  to  explain.  It  is  like  the  idea  of  beauty  in 
this  respect.  You  know  that  a  certain  statue  or  painting  or 
symphony  is  beautiful;  but  you  cannot  describe  precisely 
what  *  beauty '  is.  One  cannot  inject  beauty  into  a  thing 
with  a  syringe.  Something  in  the  make-up  of  the  work  of  art 
gives  it  the  quality  of  beauty.  Add  a  line,  take  out  a  line, 
change  a  line  in  a  drawing,  and  its  beauty  is  gone;  and  yet 
beauty  is  not  a  line  or  a  group  of  lines. 

Like  beauty,  consciousness  is  a  quality  or  characteristic  of 
things  —  it  is  not  itself  a  concrete  thing.  Consciousness  is 
not  something  poured  into  the  mind;  it  is  a  characteristic  of 
mental  life.  Given  the  proper  conditions  and  there  is  con- 
sciousness. Alter  the  conditions  and  there  is  no  conscious- 
ness —  just  as  in  the  case  of  beauty. 

'  The  third  stage,  the  process  of  acting  and  responding,  is  treated  in  chs. 
x-xii 


CH.  vi]         NATURE  OF  CONSCIOUSNESS^-^/  188 


Nothing  has  given  more  trouble  to  ^tb  BlignanSr  in  psychol- 
ogy  than  the  notion  of  consciousn^s.  The  word  itself  is 
mysterious  and  forbidding.^  It  is  well  to  recognize  this  diflfi- 
culty  at  the  start  and  try  to  get  better  acquainted  with  the 
term. 

To  be  conscious,  means  simply  to  have  sensations  and  any 
sort  of  experiences.  You  are  conscious  when  you  are  receiving 
impressions  and  putting  them  together  into  perceptions, 
thoughts,  and  the  like.  When  you  are  in  a  swoon  or  a  dream- 
less sleep  and  are  getting  no  impressions,  you  are  not  con- 
scious. In  other  words,  consciousness  is  merely  a  shorthand 
term  used  to  express  the  fact  that  perceptions,  thoughts,  and 
the  Uke  are  part  of  one's  personal  mental  life. 

We  are  conscious  only  when  stimuh  start  nerve  impulses 
and  these  impulses  reach  the  brain.  There  are  cases  where 
stimuli  excite  nerve  impulses  which  do  not  reach  the  cortex; 
in  such  cases  we  are  not  conscious,  though  the  stimuli  produce 
important  reflex  results  and  consequently  belong  to  the  realm 
of  psychology.  The  reflex  eye-wink  is  an  example  of  this. 
In  many  cases  the  sensory  nerve  impulses  are  integrated  in 
the  brain  centers  and  cause  coordinated  responses,  yet  the 
impressions  are  not  joined  up  with  our  general  train  of 
conscious  experiences.  When  we  are  walking  with  a  friend 
and  are  busy  talking,  we  do  not  notice  the  objects  about  us; 
yet  we  step  up  and  down  and  avoid  obstacles  quite  as  well  as 
if  we  were  fully  aware  of  our  surroundings. 

Experiences  which  form  part  of  our  Ufe  of  stimulation  and 
response,  yet  do  not  enter  into  our  personal  mental  life,  are 
called  subconscious.  Our  subconscious  mental  life  is  quite  as 
important  for  psychology  as  consciousness.  The  lower  brain 
centers  are  constantly  receiving  sensory  impressions  and 

^  Some  psychologists  get  around  the  difficulty  by  dropping  the  notion  of 
consciousness  altogether  and  studying  behavior.  The  result  is  a  rather 
fragmentary  science.  It  is  like  trying  to  study  art  and  ignoring  the  notion 
of  beauty. 


124  CONSCIOt^  LIFE  fcH.  vi 

sending  out  motor  impulses  that  are  never  associated  with 
our  conscious  hfe.  Many  of  our  thoughts  and  decisions  are 
determined  in  large  measure  by  previous  subconscious  experi- 
ences. All  the  activities  of  the  nerve  centers,  whether  con- 
scious or  subconscious,  must  be  reckoned  with  in  psychology; 
they  are  all  factors  in  determining  our  responses. 

The  Brain  and  Consciousness.  —  The  really  difficult  prob- 
lem is  not  what  consciousness  is,  but  how  it  is  related  to 
brain  activity.  In  discussing  each  of  the  senses  we  traced  the 
course  of  the  nerve  impulse  from  the  receptor  to  the  center. 
When  an  impulse  in  the  optic  nerve  reaches  the  visual  center, 
we  see.  When  an  impulse  in  the  auditory  nerve  reaches  the 
auditory  center,  we  hear.  And  so  for  each  of  the  other  nine 
senses.  But  just  how  the  brain  activity  produces  sensations, 
memories,  and  other  experiences  is  not  known.' 

This  much  seems  certain:  Every  single  perception  and 
every  step  in  our  thinking  means  some  definite  nervous  activity. 
Our  thoughts  never  for  an  instant  proceed  without  brain 
activity.  If  the  brain  is  in  any  way  impaired,  thinking  or 
memory  or  perception  or  some  other  mental  process  is  dis- 
turbed. Insanity  is  caused  by  some  injury  to  the  brain. 
Lapses  of  memory,  swooning,  sleep,  are  brought  about  by 
temporary  changes  in  the  condition  of  the  brain. 

Psychology  need  not  be  tied  to  any  special  theory  of  how 
brain  and  consciousness  are  related.  But  the  facts  just  men- 
tioned point  to  the  conclusion  that  whenever  we  think  or  per- 
ceive, our  brain  is  acting  in  certain  corresponding  ways. 
In  other  words,  the  psychologist  can  study  his  thoughts  and 
memories,  his  perceptions  and  emotions,  in  place  of  the  cen- 
tral nerve  processes  which  accompany  them.  We  have  no 
means  of  measuring  brain  processes  as  we  can  measure  hght 

*  There  are  several  theories  which  attempt  to  explain  the  relation.  The 
older  view  is  that  the  mind  is  in  the  brain,  and  that  mind  and  brain  interact, 
A  newer  theory  is  that  thought  and  brain  activity  are  really  the  same  event, 
observed  in  two  different  ways. 


CH.  VI]  BRAIN  AND  CONSCIOUSNESS  125 

waves  or  muscular  contraction.  The  investigation  of  our 
own  experiences  supplies  this  lack. 

Self -observation.  —  One  of  the  most  important  things  in 
studying  psychology  is  to  examine  your  own  experiences,  or 
states  of  mind.  The  basal  facts  of  psychology  were  discov- 
ered by  men  observing  their  own  thoughts  and  perceptions, 
and  reporting  what  they  observed.  This  method  of  study  is 
called  self-observation,  or  introspection. 

At  first  glance  it  seems  simple  enough  to  observe  our  own 
experiences.  We  have  them  with  us  constantly  and  need 
only  direct  our  attention  toward  them.  Yet  when  we  try  it 
out  we  find  that  it  is  not  easy  to  attend  to  our  experiences 
carefully  and  faithfully  or  to  report  our  observations  accu- 
rately. The  old  error  about  the  five  senses  persisted  through 
many  generations.  It  was  kept  alive  because  men  did  not 
examine  their  experiences  carefully.  They  reported  not 
what  they  observed  for  themselves  but  what  they  had  read 
and  heard. 

Just  as  bad  mistakes  have  been  made  in  other  sciences  and 
have  retarded  their  development.  In  physics  men  persisted 
in  beUeving  that  heavy  bodies  fall  faster  than  light  ones; 
in  chemistry  they  stuck  to  the  idea  that  there  are  only  four 
elements  —  earth,  air,  fire,  and  water.  These  notions  seemed 
so  self-evident  that  for  a  long  time  no  one  took  the  trouble 
to  put  them  to  actual  test. 

In  psychology  the  material  is  so  very  accessible  that  the 
student  is  slow  to  realize  that  training  is  needed  before  he 
can  observe  it  properly.  Some  of  the  most  absurd  mistakes 
in  psychology  examinations  occur  in  answering  questions  for 
which  the  student  has  the  material  right  with  him:  for 
instance,  he  has  only  to  wink  his  eyes  to  observe  after- 
sensations.  Casual  or  haphazard  noticing  of  our  own  experi- 
ences is  not  scientific  psychology.  Self-observation,  as  a 
scientific  method,  means  careful  and  often  minute  attention 
to  the  flow  of  conscious  experiences;  it  means  also  giving 


126  CONSCIOUS  LIFE  [ch.  vi 

exact  reports  of  our  observations.  Both  demand  considerable 
training  before  the  results  are  accurate.  If  the  student  has 
carefully  performed  the  practical  exercises  in  the  previous 
chapters,  he  will  already  have  advanced  a  considerable  way 
in  the  art  of  self-observation. 

How  Conscious  Experiences  are  Formed.  —  When  sensory 
nerve  impulses  reach  the  brain  centers,  they  are  combined 
and  altered  in  many  ways  before  the  motor  nerve  impulses 
are  ready  to  start  a  coordinated  movement.  When  we  enter 
a  shop  our  eyes  are  stimulated  by  many  objects  which  give 
us  a  great  mass  of  color  sensations.  These  elementary  bits 
of  sensation  are  combined  at  once  into  vivid  perceptions  of 
the  various  objects  in  the  shop;  the  perceptions  start  a  train 
of  thoughts  and  memories  which  continue  until  we  decide 
which  way  to  turn  and  what  things  to  examine  and  purchase. 

Sensations  are  merely  the  bits  of  material  out  of  which  our 
experiences  are  constructed.  The  quality  and  intensity  of 
the  separate  sensations  depend  on  the  nature  of  the  objects 
which  stimulate  the  receptor  organs,  and  on  the  nature  of 
the  receptor  organs  themselves,  far  more  than  on  the  nervous 
system  and  its  activity.  Certain  visual  sensations  are  *  red  ' 
because  red-giving  light  waves  strike  the  eye  and  because  the 
retina  is  capable  of  distinguishing  these  rays  from  others. 
Certain  sensations  are  *  loud  '  because  intense  sound  waves 
strike  the  ear  and  make  the  ear-drum  vibrate  vigorously. 
This  is  true  of  all  sensations. 

But  when  we  examine  the  experiences  built  up  out  of  these 
sensation  elements  the  opposite  is  true.  Their  composition 
dep)ends  far  more  on  nervous  processes  than  on  the  stimuli. 
The  nervous  operations  which  result  from  the  various 
properties  of  nerve  substance,'  are  the  principal  agencies  in 
forming  our  experiences.  For  instance,  conscious  attention 
varies  with  nervous  fatigue :  fatigue  of  the  nerve  substance  in 
the  brain  means  inattention;  restoration  of  this  substance 
*  These  were  described  in  ch.  iii;  see  pp.  44-48. 


CH.  VI]       FORMATION  OF  EXPERIENCES  127 

means  attention.  Memory  or  revival  of  old  experiences 
varies  with  the  nervous  operation  of  retention.  Association 
of  ideas  depends  on  nervous  conduction.  There  are  import 
tant  conscious  operations,  or  mental  processes,  corresponding 
to  each  of  the  principal  properties  of  nerve  substance  (ch.  iii). 

Mental  Processes:  Impression  and  Suggestion.  —  The 
two  most  prominent  mental  processes  are  that  we  are  im- 
pressed by  objects  and  events,  and  that  one  experience  sug- 
gests another.  Impression  corresponds  to  nervous  excitation 
and  suggestion  corresponds  to  nervous  conduction. 

Impression  means  that  a  sensation  or  some  other  experience 
is  aroused.  It  occurs  when  the  central  neurons  are  excited  by 
nerve  impulses.  You  see  this  book  —  you  get  a  visual  im- 
pression of  it.  The  impression  is  due  to  nerve  impulses  from 
the  eye  which  excite  the  visual  center  in  your  brain.  Anger 
is  an  experience  that  arises  when  nerve  impulses  from  your 
bodily  organs  and  motor  organs  excite  some  of  your  brain 
centers.     And  similarly  for  other  experiences. 

Suggestion  is  a  form  of  mental  association:  one  thought 
passes  over  into  another.  The  thought  of  peaches  suggests  to 
me  the  island  of  Corfu,  where  I  tasted  specially  delicious 
peaches.  The  peach  thought  and  the  Corfu  thought  are 
associated  together;  that  is,  the  thought  of  peaches  passes 
over  into  the  thought  of  Corfu.  In  terms  of  nervous  activity 
what  happens  is  that  the  nerve  impulses  pass  from  one  center 
to  another,  where  they  assume  a  difiFerent  form. 

Revival  and  Attention.  —  Revival  and  attention  are  two 
other  mental  processes.  Revival  or  memory  corresponds  to 
the  nervous  process  of  retention.  The  set  or  trace  left  by 
previous  nerve  impulses  in  the  brain  centers  makes  it  possible 
for  these  centers  to  be  aroused  later  in  the  same  way;  the 
form  of  the  earlier  impulse  is  reproduced  because  of  the  trace 
which  it  leaves  behind.  Memory  images  are  the  conscious 
experiences  which  arise  as  a  result  of  this  revival;  they  are 
reproductions  of  earlier  impressions.    You  remember  a  cer- 


128  CONSCIOUS  LIFE  [ch.  vi 

tain  birthday  party  because  the  brain  centers  which  retain 
traces  of  that  group  of  experiences  have  been  excited  again, 
renewing  the  experience  to  a  certain  extent. 

Attention  is  related  (inversely)  to  the  nervous  process  of 
fatigue.  Some  parts  of  an  experience  are  more  vivid  than 
others.  When  you  are  reading,  the  printed  words  are  vivid. 
Sounds  that  occur  at  the  same  time  are  not  attended  to;  — 
the  stimuli  may  be  quite  intense,  but  the  experiences  are  not 
vivid.  The  rubbing  of  your  clothes  and  other  incidental 
stimuli  are  generally  unnoticed.  In  reading  you  attend  to 
only  a  few  words  at  a  time;  the  rest  of  the  page  is  scarcely 
noticed.  All  this  means  that  out  of  the  many  stimuli  which 
occur  at  any  moment,  only  a  few  send  impulses  straight 
through  to  your  brain  centers  without  hindrance;  the  others 
are  blocked  by  resistance  due  in  part  to  fatigue  or  exhaustion 
of  certain  synapses  —  they  are  not  attended  to.  The  greater 
the  fatigue,  the  theater  is  the  degree  of  inattention. 

Attention  means  the  focusing  of  certain  impressions. 
Other  impressions  that  occur  at  the  same  time  are  out  of 
focus;  they  are  said  to  be  in  the  margin  or  fringe  of  conscious- 
ness. The  different  degrees  of  vividness  or  focusing  that 
characterize  the  several  portions  of  our  total  experience  at 
any  given  moment  depend  on  variations  in  the  chemical 
conditions  of  the  several  neurons  concerned.  In  other 
words,  the  vividness  of  an  experience  depends  not  so  much 
on  the  strength  of  the  stimulus,  as  on  the  condition  of  our 
brain.  Attention  is  partly  involuntary  and  partly  under 
our  own  control.  A  very  loud  sound  will  force  itself  upon  us 
and  drive  all  else  out  of  the  focus;  on  the  other  hand  a  faint 
impression  may  be  brought  voluntarily  to  the  focus  if  it  is 
of  special  interest;  the  football  player  sees  distinctly  certain 
slight  movements  on  the  part  of  his  opponents,  which  give  a 
clue  to  the  play. 

Composition  and  Discrimination.  —  The  third  pair  of 
mental  processes  are  composition  and  discrimination;  they 


CH.  VI]  MENTAL  PROCESSES  129 

correspond  to  the  collection  and  distribution  of  nerve  im- 
pulses. The  composition  of  sensations  into  larger  experiences 
occurs  when  the  impulses  from  several  distinct  nerve  paths 
are  collected  together  in  a  single  center. 

There  are  two  difiFerent  sorts  of  mental  composition: 
fusion  and  colligation.  In  fusion  the  elementary  sensations 
are  so  merged  together  that  it  is  difficult  to  pick  them  apart. 
The  experience  is  a  total  consolidated  eflFect.  A  typical  case 
of  fusion  occurs  in  musical  chords.  The  stimuli  for  the  chord 
C-E-G  are  three  separate  tones.  When  they  are  all  struck 
together,  the  resulting  sensation  is  a  single,  compound  clang, 
in  which  the  three  tones  are  so  fused  together  that  only  a 
practiced  musician  can  pick  out  any  one  of  them  from  the 
harmony. 

Colligation  is  another  sort  of  composition,  in  which  the 
individual  components  keep  their  identity.  It  occurs  notably 
in  sight.  A  painting  does  not  appear  to  be  a  patchwork  of 
separate  colors  on  a  canvas;  we  see  it  as  a  single  picture, 
representing  some  definite  scene.  In  colligation  it  is  easy 
to  distinguish  the  different  parts;  they  do  not  merge,  as  in 
fusion,  but  appear  side  by  side,  as  a  pattern  or  picture. 

Touch  impressions  generally  unite  by  colligation;  taste  and 
smell  by  fusion.  Sensations  from  different  senses,  due  to  the 
same  object,  fuse  together.  Fried  mushrooms  are  round  and 
brown,  odorous,  sweet,  warm,  and  soft;  it  is  not  easy  to  sepa- 
rate any  one  of  these  sensations  from  the  total  effect  of 
a  *  luscious  food.'  A  crowbar  always  looks  heavy  to  you  if  you 
have  once  tried  to  lift  one.  The  fusion  is  so  strong  that  the 
visual  and  muscle-sense  elements  stick  together  even  when 
you  look  at  it  without  lifting  it. 

Discrimination  occurs  when  a  nerve  impulse  in  the  central 
region  is  distributed  into  two  or  more  different  paths.  The 
mental  process  is  a  separation  of  two  or  more  elements  in  a 
given  experience.  It  is  the  opposite  of  composition.  In 
looking  at  a  person's  face  we  first  see  it  as  a  single  object. 


f 


130  CONSCIOUS  LIFE  [ch.  vi 

By  the  process  of  discrimination  we  pick  out  the  eyes,  nose, 
mouth,  and  other  features.* 

All  our  experiences  are  made  up  of  elementary  sensations 
which  have  been  '  whipped  into  shape  '  by  these  mental 
processes.  In  examining  the  various  sorts  of  experience  we 
shall  have  to  refer  constantly  to  these  operations.  They  are 
brought  together  in  Table  V,  with  the  corresponding  nervous 
processes. 

Table  V.  —  Fundamental  Conscious  Operations 

Conscious  0-peraiion  Nervous  Operation 

Impression  (sensibility)  Excitation 

Suggestion  (successive  association)  Conduction 

Revival  (memory)  Retention 

Attention  (vividness,  focusing)  Fatigue 

Composition  (simultaneous  association)  Collection 

Discrimination  Distribution 

Transformation  (mental  chemistry)  Modification 

Kinds  of  Experience.  —  Any  definite  state  of  mind  or  con- 
sciousness is  called  an  experience.  When  we  look  around  the 
room  we  get  a  distinct  visual  impression  of  the  table  and 
chairs  and  floor  and  walls  and  various  objects  about  us.  This 
composite  experience  is  known  as  a  perception;  we  perceive 
the  world  as  presented  to  us  by  the  visual  receptors^  and 
nerves.  When  we  are  ill  at  ease  or  in  pain,  the  experience  is 
of  a  very  different  sort :  it  is  called  a. feeling.  Our  motor  senses 
tell  us  how  we  move  and  how  our  body  is  placed;  this  type  of 
experience  has  no  familiar  name,  because  it  is  popularly  con- 
fused with  volition.-    Psychologists  call  it  a  conation. 

Perceptions,  feelings,  and  conations  are  three  fundamental 
sorts  of  experience.     In  each  case  the  state  of  mind  is  made 

^  Besides  these  six  mental  processes  there  is  another  called  transformation 
or  mental  chemistry.  When  several  impressions  combine  together  the  result 
is  often  quite  unlike  any  of  the  components,  just  as  the  properties  of  water 
are  unlike  those  of  the  oxygen  and  hydrogen  which  compose  it.  Mental 
transformation  depends  on  the  modification  of  nerve  impulses. 

*  Sounds  are  perceived  through  the  auditory  receptors.  All  the  external 
senses  yield  perceptions. 


CH.  VI]         VARIETIES  OF  EXPERIENCES  131 

up  largely  of  sensations  from  one  of  the  three  great  groups  of 
senses.  Perceptions  are  composed  chiefly  of  external  sen- 
sations; feelings,  of  systemic  sensations;  conations,  of  motor 
sensations.  There  is  another  fundamental  kind  of  experi- 
ence called  imagery,  which  is  made  up  largely  of  memories 
and  other  ideas.  Memories  are  revivals  of  past  sensations. 
They  are  not  directly  due  to  present  stimuli.  When  you 
remember  the  scene  at  your  last  Thanksgiving  dinner,  the 
experience  is  not  a  visual  impression.  The  memory  is 
aroused  by  some  sensory  stimulus,  but  you  do  not  at  this 
present  moment  sej  the  table  and  cooked  turkey  and  mince 
pie  which  gave  you  the  original  experience.' 

Besides  these  four  fundamental  types  there  are  several 
important  secondary  kinds  of  experiences  which  are  com- 
posed of  elements  from  two  or  more  different  sources.  For 
instance,  an  emotion  is  composed  of  sensations  coming  from 
both  the  systemic  and  motor  senses.  When  we  are  very 
angry  we  have  very  intense  organic  sensations  and  very 
intense  muscle  sensations.  The  experience  of  anger  is  a 
combination  of  these  two  elements.  The  various  funda- 
mental and  secondary  experiences  which  occur  in  our  mental 
life,  and  the  elements  of  which  they  are  composed,  are  shown 

Table  VI.  —  Classes  of  Experiences 


Fundamental 
Ex'perienee  Dominating  Component 

Perception External  Sensations 

Imagery External  Ideas 

Feeling  Systemic  Sensations 

Conation Motor  Sensations 

Secondary 
Ex'perienee  Dominating  Components 

Emotion  Systemic  and  Motor  Sensations 

Sentiment Ideas  and  Systemic  Sensations 

Volition  Ideas  and  Motor  Sensations 

Thought  and  Language  (Social) ....  Ideas  and  Motor  Sensations 

Ideals Ideas;  Systemic  and  Motor  Sensations 

*  Memory  is  discussed  in  ch.  viiL 


132  CONSCIOUS  LIFE  [ch.  vi 

in  Table  VI.  We  shall  take  them  up  one  by  one  in  the  next 
few  chapters. 

One  thing  should  be  constantly  borne  in  mind  when  we 
examine  our  experiences :  our  state  of  mind  at  any  moment  is 
rarely  a  pure  experience  of  a  single  sort.  When  we  look  at 
the  objects  around  us,  our  perceptions  are  always  tinged  with 
memory  or  feeling;  the  paper-weight  looks  heavy,  the  razor- 
blade  looks  painfully  sharp.  Our  feelings  are  usually  ac- 
companied by  some  external  impressions;  and  so  on.  But 
every  experience  is  composed  largely  of  a  certain  type  of 
sensation  (or  ideas)  or  else  largely  of  two  types.  A  percep- 
tion is  an  experience  whose  prominent  elements  are  external 
sensations;  and  so  of  other  experiences.  In  every  case  certain 
prominent  ingredients  fix  the  character  of  the  experience 
state;  they  are  its  dominant  components. 

Subconscious  Experience.  —  Many  nerve  impulses  do  not 
reach  the  higher  centers  in  the  brain  and  do  not  give  con- 
scious experiences.  Yet  these  subconscious  processes  may 
be  essential  factors  in  our  responses.  When  you  are  riding  a 
bicycle  you  are  not  aware  of  the  static  sensations  from  the 
semicircular  canals;  but  these  sensations  of  balance  are  occur- 
ring all  the  time  in  the  center  for  the  static  sense.  They 
start  a  constant  succession  of  motor  impulses  to  the  muscles 
of  the  arms  and  hands,  which  produce  slight  movements  of 
the  handle-bar  to  right  or  left;  these  movements  keep  you 
balanced  and  prevent  the  machine  from  falling  over.  How 
you  learn  to  make  these  adjustive  movements  need  not  be 
discussed  here.'  The  point  is  that  you  do  make  them  with- 
out being  conscious  of  the  action. 

Sometimes  we  are  confronted  with  a  difficult  mathematical 
problem  which  we  cannot  solve.  After  puzzling  over  it  for  a 
long  time  we  drop  it  and  go  about  some  other  business. 
Then  all  of  a  sudden,  without  any  apparent  reason,  the  solu- 
tion of  the  problem  flashes  before  us  when  we  are  thinking  of 

^  See  ch.  xi. 


CH.  vi]  SUBCONSCIOUS  EXPERIENCE  133 

something  entirely  different.  The  problem  seems  to  have 
been  worked  out  subconsciously. 

A  clock  strikes  when  you  are  reading  and  you  do  not 
notice  it.  A  minute  or  two  later  you  recall  that  it  struck 
four  times. 

You  meet  a  man  —  a  perfect  stranger  —  in  some  gather- 
ing, and  at  once  take  a  dislike  to  him.  You  cannot  explain 
this  dislike  for  a  long  time.  Finally  you  realize  that  he  re- 
minds you  strongly  of  some  one  you  know,  whose  person- 
ality is  distasteful  to  you. 

You  go  out  for  a  walk  and  take  a  certain  path  because  of 
the  interesting  scenery  it  offers.  That  is,  you  believe  this 
to  be  the  reason  for  your  choice.  You  return  disappointed, 
and  suddenly  become  aware  that  you  subconsciously  expected 
to  encounter  a  certain  attractive  damsel  on  the  way. 

Sometimes  immediately  after  waking  in  the  morning  I  can 
think  of  nothing  but  annoying  blunders  made  by  members  of 
the  family  or  others  —  perhaps  months  ago.  This  fault- 
finding attitude  is  due  to  subconscious  systemic  sensations 
of  indigestion,  not  to  anything  in  the  external  situation.  On 
first  waking,  the  digestive  conditions  overweigh  the  objective 
facts,  and  unwittingly  control  my  thoughts,  till  I  realize  the 
reason  and  see  the  absurdity  of  this  attitude. 

Instances  of  subconscious  factors  in  mental  life  might  be 
multiplied  indefinitely.  Reasoning,  memory,  emotion,  motor 
coordination  —  all  proceed  at  times  subconsciously.  Often 
these  subconscious  attitudes  or  processes  are  valuable 
adjuncts  to  our  conscious  processes,  as  in  the  first  example 
given.  In  other  cases  they  interfere  with  the  normal  opera- 
tion of  our  mental  life.  This  is  particularly  true  of  unpleas- 
ant experiences  or  thoughts  which  we  are  ashamed  of  and 
wish  to  ignore.  We  try  to  forget  them,  and  we  succeed  so 
far  as  our  personal  consciousness  is  concerned.  But  their 
traces  may  persist  in  the  subconscious  framework  of  our 
being.     They  crop  out  in  imexpected  and  annoying  ways; 


134  CONSCIOUS  LIFE  [ch.  vi 

sometimes  they  are  betrayed  by  slips  of  the  tongue,  disquiet- 
ing dreams,  or  inexplicable  actions. 

Psychoanalysis.  —  Attention  has  recently  been  called  to 
^  this  subconscious  phase  of  mental  life  by  the  investigations  of 
Sigmund  Freud  and  others  who  have  followed  his  method  of 
investigation.  These  observers  find  that  if  you  let  yom* 
thoughts  proceed  naturally,  without  repression  or  guidance, 
frequently  you  will  bring  into  the  field  of  consciousness  some 
subconscious  memories  or  tendencies  of  whose  existence  you 
were  not  aware. 

A  certain  man  has  an  unconquerable  repugnance  to  the 
contact  of  fur.  He  is  unable  to  explain  it.  Under  expert 
handling,  a  train  of  thought  is  started,  beginning  with  the 
idea  of  fur.  He  is  led  through  quite  a  succession  of  memo- 
ries, and  finally  recalls  an  incident  of  early  childhood,  long 
forgotten,  of  being  attacked  by  a  shaggy  dog. 

This  method  of  bringing  the  subconscious  into  the  fore- 
ground is  called  psychoanalysis.  It  has  been  used  with  good 
effect  by  physicians  to  enable  patients  to  conquer  unreason- 
ing fears  and  obsessions.  Psychoanalysis  is  based  on  sound 
psychological  principles;  for  our  mental  life  depends  largely 
on  subconscious  memory  traces  and  on  the  attitudes  which 
they  have  developed.  It  is  also  a  fact  that  when  we  dis- 
cover the  real  origin  of  a  baseless  fear  we  can  often  over- 
come it. 

We  must  be  cautious,  however,  in  interpreting  the  results 
obtained  by  this  method.  There  is  danger  of  carrying  our 
conclusions  too  far,  as  the  followers  of  Freud  have  done  re- 
peatedly. Three  great  faults  are  found  in  the  books  which 
treat  of  subconscious  life  from  this  standpoint: 

(1)  They  convey  the  idea  that  the  subconscious  part  of  our 
being  is  a  very  highly  organized  personality.  Freudians  speak 
as  if  there  were  a  subconscious  person  (the  *  censor  ')  inside 
us,  who  forces  us  to  repress  certain  thoughts  and  desires. 
As  a  matter  of  fact,  the  subconscious  part  of  our  personality 


CH.  VI]  PSYCHOANALYSIS  135 

is  not  nearly  so  well  organized  as  the  conscious.  It  is  rather 
a  lot  of  independent,  partly  organized  attitudes  and  tenden- 
cies, which  enter  separately  into  our  life.  The  '  fear  of  fur  ' 
is  one  such  tendency;  the  desire  to  meet  a  certain  attractive 
girl  is  an  entirely  separate  tendency.  Each  of-  these  sub- 
conscious motives  works  independently,  not  through  a  gen- 
eral '  subconscious  self.' 

(2)  There  is  danger  also  of  forcing  the  interpretation. 
Some  writers  become  so  fascinated  with  the  notion  of  sub- 
consciousness that  they  use  it  to  explain  everything.  A  lady 
says  to  her  physician,  "  Please  do  not  give  me  big  bills  "  — 
meaning  '  big  pills.'  Immediately  it  is  assumed  that  she  was 
thinking  subconsciously  of  his  high  charges.  It  is  more 
likely  that  the  letter  *  b  '  in  '  big '  was  carried  over  to  the 
next  word  and  happened  to  make  sense.  Had  she  said  '  pig 
pills '  or  '  pig  bills  '  the  purely  vocal  nature  of  the  blunder 
would  have  been  obvious. 

We  must  be  especially  careful  not  to  attach  importance  to 
the  symbolic  interpretation  which  psychoanalysts  assign  to 
dreams  and  trains  of  thought.  They  are  usually  far-fetched 
or  fanciful.  In  interpreting  dreams  they  say  that  the  sim 
stands  symboUcally  for  the  dreamer's  father;  a  woman 
dreamed  of  is  symbolic  of  his  mother  or  wife.  A  number 
symbolism  has  been  worked  out  which  is  as  fantastic  as  that 
of  the  fortune-tellers. 

(3)  Writers  on  the  subconscious  assign  too  much  sexual 
significance  to  the  hidden  motives  of  action.  The  generative 
processes  undoubtedly  play  a  large  part  in  human  life  —  far 
more  than  we  usually  recognize.  Civilized  man  has  been 
taught  to  repress  his  sexual  feelings,  and  the  result  is  to  mag- 
nify their  importance  in  our  silent  thinking.  But  there  are 
other  important  factors  in  our  subconscious  life.  Nutrition 
is  a  powerful  motive.  The  nutritive  function  dates  back  to 
the  very  dawn  of  life  —  long  before  there  were  two  sexes. 
Avoidance  of  pain  and  the  urge  toward  general  activity  are 


W6  CONSCIOUS  LIFE  [ch.  vi 

also  important  motives  of  conduct.  In  studying  mental  life 
we  should  not  be  prudish  and  ignore  the  sex  factor;  on  the 
other  hand  we  must  not  be  carried  away  by  the  zeal  of  uni- 
form interpretation  so  far  as  to  attribute  every  subconscious 
motive  to  this  one  source. 

These  cautions  are  needed  to-day  because  the  method  of 
psychoanalysis  has  recently  received  considerable  attention 
and  has  been  exaggerated  and  distorted.  The  method  itself 
is  perfectly  correct.  By  its  use  we  can  often  arrive  at  a 
knowledge  of  many  factors  in  our  subconscious  life  which 
without  it  remain  hidden:  motives  become  clear  which  are 
otherwise  incomprehensible.  The  danger  lies  merely  in 
interpreting  the  results  unscientifically.  If  the  above  cau- 
tions are  observed  there  is  little  danger  of  misusing  psycho- 
analysis.^ 

Varieties  of  Subconsciousness.  —  The  term  subconscious 
experiences  may  be  applied  to  several  different  sorts  of  events 
in  mental  life.  These  fall  into  two  classes:  Subliminal  con- 
sciousness and  subordinate  consciousness. 

(1)  Subliminal  Experiences:  These  are  due  to  stimuli 
which  are  so  faint  that  the  result  falls  below  the  threshold  or 
limit  of  consciousness;  there  is  no  conscious  impression  at  all. 
Or  two  stimuli  may  differ  so  slightly  that  we  do  not  con- 
sciously discriminate  between  them. 

A  laboratory  experiment  illustrates  this.  The  Jastrow 
cylinders  are  hollow  cylinders  of  hard  rubber  with  removable 
ends,  which  can  be  readily  grasped  and  lifted.  [Fig.  51.] 
In  this  experiment  we  take  two  of  them  and  put  weights 
inside  so  that  one  is  slightly  heavier  than  the  other,  say  150 
and  153  grams.  If  you  lift  first  one,  then  the  other,  they 
seem  about  the  same  weight. 

*  An  amusing  satire  on  the  method  is  contained  in  one  of  the  Provincetown 
Plays  called  'Suppressed  Desires.'  One  character  dreams  of  a  hen  stepping 
about;  the  interpreter  declares  she  was  subconsciously  thinking  of  a  certain 
man  named  Stephen. 


CH.  vi]        TYPES  OF  SUBCONSCIOUSNESS  137 

Now  let  the  subject  close  his  eyes  and  let  the  experimenter 
give  him  one  cyUnder  after  the  other  to  lift  and  compare; 
let  him  judge  (or  guess)  which 
is  the  heavier.    Repeat  this  a 
large  number  of  times,  giving 
him  the  two  cylinders  now  in 
one  order,  now  in  the  other.    If 
the  subject  were  merely  guess- 
ing, half  of  his  answers  would 
be  right  and  half  wrong.     But     ^^°-  ^^- "  J^sthow  Cylinders 
it  is  found  that  in  the  long  run      ^,f  t*°  *"'  ^^f  ability  to  discriminate 

o  small  differences  in  weight,  by  lifting  or 

the    subject   wiU    give  decidedly  ]>y  pressure  on  the  skin,     shot  is  pouted 

,  _.  »     •    I  into  each  cylinder  till  the  desired  weight 

more  than  fifty  per  cent  of  right  U  obUined.    When  the  ends  are  screwed 

r^-^^-^^-^^     ^,,^-^    t-l.^-.-^'U    U-^ ,,  on,  the  cylinders  look  and  feel  alike. 

answers,  even  though  he  may 

beUeve  he  is  only  guessing.  In  other  words,  the  slight  difiFer- 
ence  between  the  two  stimuli,  even  though  it  is  so  small  as 
not  to  be  consciously  noticed,  has  a  real  effect  on  our  experi- 
ences. It  influences  our  judgments  to  the  extent  which  the 
percentage  indicates. 

Similar  experiments  may  be  made  with  pairs  of  lines  that 
are  nearly  equal,  or  with  other  pairs  of  slightly  different 
stimuli.  The  results  indicate  the  presence  of  subliminal  ele- 
ments in  our  experiences. 

Somewhat  the  same  sort  of  elements  occur  in  the  '  margi- 
nal '  portions  of  our  ordinary  experiences.  When  you  look 
attentively  at  any  object  the  things  at  the  far  end  of  the 
visual  field  are  hazy  and  almost  unnoticed.  They  may  not 
be  quite  subliminal,  yet  they  do  not  enter  into  the  general 
picture  as  conscious  factors.  Or  again,  if  you  are  reading, 
the  conversation  and  other  noises  about  you  are  marginal. 
In  such  cases  the  second  stimulus  is  not  necessarily  very 
faint,  but  the  nerve  impulses  which  it  starts  do  not  pene- 
trate to  the  higher  centers  except  in  a  faint  degree.  Their 
passage  is  hindered  by  fatigue  of  the  synapses,  which  is 
equivalent  to  *  inattention.'  Consequently  the  resulting 
sensations  in  the  higher,  conscious  centers  are  marginal 


188  CONSCIOUS  LIFE  [ch.  vi 

(2)  Subordinate  Levels  of  Experience:  Here  the 
sensory  impulse  does  not  connect  up  with  our  present  per- 
sonal experience  at  all.  Its  effects  are  inhibited  at  the  lower 
center.  The  case  of  the  clock  striking  without  your  noticing 
it  illustrates  this;  the  original  experience  did  not  form  part 
of  your  personal  field  of  consciousness,  but  it  did  belong  to  a 
subordinate  field  of  consciousness,  as  shown  by  the  fact  that 
you  recalled  it  afterwards. 

In  other  cases  the  experience  never  gets  to  oiu*  personal 
consciousness,  and  we  are  inclined  to  doubt  whether  the 
effect  is  not  purely  *  physiological '  and  unconscious.  Some 
morning  when  I  am  in  my  laboratory  it  begins  to  rain.  I 
wonder  whether  I  closed  my  bedroom  window  before  leaving 
the  house.  Hard  as  I  try,  I  cannot  recall  closing  it.  On 
returning  to  the  house  I  find  the  window  closed.  I  did  close 
it,  for  no  one  else  has  been  in  the  room.  Did  I  close  the 
window  consciously  or  not? 

We  may  treat  all  such  dissociated  experiences  as  *  sub-con- 
scious ';  that  is,  they  are  of  the  same  sort  as  our  conscious 
experiences,  except  that  they  are  not  part  of  our  personal 
conscious  life;  they  are  experiences  of  our  lower  centers  — 
not  of  the  cortically  organized  self.  It  is  helpful  to  regard 
even  pure  reflexes,  such  as  winking,  as  subconscious.  This 
view  enables  us  to  bring  all  experiences  and  all  mental  Ufe 
into  one  general  notion.* 

Hyperesthesia  and  Anesthesia.  —  Stimuli  sometimes  have 
a  more  mtensive  effect  than  usual.  This  is  called  hyperes- 
thesia. When  we  are  in  a  high-strung  nervous  state  we  can 
hear  faint  sounds  which  ordinarily  would  not  be  detected; 
the  sense  of  hearing  is  '  hyperesthetic'  Visual  hyperesthesia 
occurs  frequently.  A  hypnotized  person  is  able  to  distinguish 
between  blank  sheets  of  paper,  which  look  alike  to  the  ordi- 

'  In  many  text-books  the  reflexes  and  instincts  are  treated  as  purely 
physiological  activity  and  are  not  regarded  as  mental  acts.  This  view  is 
admissible,  but  it  limits  the  field  of  psychology  unduly. 


CH.  VI]  DEGREES  OF  SENSITIVITY  139 

nary  eye.  Tell  him  that  one  sheet  is  a  photograph  of  X, 
another  a  picture  of  Y,  a  third  of  Z,  and  he  will  pick  them 
out  correctly  after  they  have  been  shuflBed.  This  abnormal 
discrimination  is  due  to  hyperesthesia:  the  hypnotic  subject 
is  unusually  sensitive  to  differences  of  texture  in  the  blank 
sheets.  Certain  persons  can  distinguish  odors  much  better 
than  others.  They  are  hyperesthetic  in  the  sense  of  smell 
as  compared  with  the  average  man.  When  we  are  more  sen- 
sitive to  touch  or  cold  in  some  special  locality  of  the  skin 
than  elsewhere,  it  is  called  local  hyperesthesia.  A  high-strung 
person  is  apt  to  have  hyperesthesia  of  all  the  senses  —  that 
is,  general  hyperesthesia.  Both  local  and  general  hyperes- 
thesia may  be  induced  by  stimulants. 

The  opposite  of  this  condition  is  undersensitivity  or  hypes- 
thesia.  It  occurs  especially  in  fatigue.  When  the  air  is 
laden  with  perfume  in  the  blossom  season  we  notice  at  first 
the  overpowering  odor;  gradually  the  odor  becomes  less  vivid 
and  at  length  it  may  appear  very  faint  indeed.  In  eating  a 
sweet  dessert  we  find  that  the  sweet  taste  becomes  gradually 
less  noticeable.  The  same  is  true  of  other  senses.  These  are 
instances  of  temporary  undersensitivity  of  the  receptor.  In 
the  same  way  the  nerves  may  be  temporarily  impaired  by 
fatigue  of  the  synapses. 

The  limiting  case  of  undersensitivity  is  anesthesia,  where 
there  is  no  sensation  whatever.  This  occurs  when  a  sensory 
nerve  is  cut  or  a  receptor  destroyed.  Anesthesia  may  also  be 
brought  about  by  the  action  of  certain  drugs  on  the  receptors. 
Cocaine  appUed  to  the  skin  deadens  the  pain  sense  tempo- 
rarily. We  have  practical  demonstrations  of  this  in  the 
dentist's  chair.  This  condition  is  local  anesthesia.  The 
numbness  of  the  arm  when  we  lie  on  it  in  bed  is  not  a  sensa- 
tion but  the  absence  of  usual  sensations;  it  is  local  tactile 
anesthesia.  Narcotic  drugs,  which  act  upon  the  nerves  di- 
rectly, produce  general  undersensitivity  and  sometimes  gen- 
eral anesthesia.    There  is  general  anesthesia  in  dreamless  sleep. 


140  CONSCIOUS  LIFE  [ch.  vi 

Hyperesthesia,  normal  sensitivity,  undersensitivity,  and 
anesthesia  really  form  a  continuous  series  containing  all  the 
various  grades  of  sensitivity.  Our  degree  of  consciousness 
and  the  tone  of  our  experiences  depend  very  largely  on  the 
general  condition  and  chemical  changes  of  our  body.  Ill- 
health,  bad  nourishment,  drugs,  impure  air,  result  in  unfa- 
vorable physiological  conditions  of  the  bodily  organs  and 
unhealthy  chemical  products  in  the  tissues.  These  harm- 
ful influences  affect  the  nervous  system  and  impair  its  ac- 
tivities, so  that  the  entire  aspect  of  the  world  may  appear 
changed. 

Relation  of  Sensitivity  to  Consciousness.  —  The  intensity 
and  vividness  of  our  experiences  depend  on  the  nervous  proc- 
esses in  the  brain  centers.  These  brain  processes  are  deter- 
mined by  two  separate  factors:  the  activity  of  the  receptors 
and  sensory  nerves,  and  the  conditions  of  the  brain  itself. 

Suppose  some  one  knocks  on  your  door.  In  order  to  hear 
the  sound  as  the  average  person  hears  it,  your  ear  and  audi- 
tory nerve  must  be  in  normal  condition.  You  may  be  deaf 
or  hard  of  hearing;  or  you  may  have  an  unusually  keen  ear 
or  be  keyed  up.  The  way  you  hear  the  sound  depends  on 
the  condition  of  the  ear  and  sensory  nerves.  The  difference 
in  sensitivity  of  the  receptors  is  the  basis  of  the  series  from 
anesthesia  to  hyperesthesia. 

Now  suppose  your  sense  of  hearing  is  normal  and  the 
auditory  impression  reaches  the  center.  Ordinarily  you  hear 
the  sound  and  say  "  Come  in."  But  you  may  be  busy  read- 
ing and  not  notice  the  sound.  Or  you  may  be  drowsy  or 
asleep.  If  you  hear  the  knocking  plainly,  you  are  conscious. 
If  you  are  inattentive,  the  experience  is  marginal.  If  the 
knocking  is  loud  and  you  do  not  hear  it  at  the  time,  its  effect 
is  subconscious  —  it  is  an  experience  of  your  lower  centers. 
If  the  sound  is  very  faint,  the  effect  may  be  subliminal.  That 
is,  your  experience  of  the  knocking  depends  not  only  on  your 
receptors  but  on  the  condition  of  your  brain.     This  is  the 


CH.  vi]  SENSITIVITY  AND  CONSCIOUSNESS         141 

basis  of  the  difference  between  vivid  consciousness,  marginal 
consciousness,  and  subconsciousness. 

Summary.  —  In  the  two  preceding  chapters  we  examined 
the  process  of  receiving  information  (sensation)  and  the 
nature  of  the  sensations  in  man.  This  chapter  takes  up 
the  question:  "  What  happens  when  the  sensory  material 
reaches  the  brain  centers?  " 

One  important  result  is  that  we  receive  the  information. 
That  is,  the  man  in  whose  brain  the  nerve  impulses  are  going 
on  is  conscious  and  has  sensations  and  various  experiences. 
Consciousness  means  that  the  man  is  alive  to  his  surround- 
ings. 

Still  more  important  is  the  fact  that  the  sensations  do  not 
remain  detached  and  unrelated.  They  are  put  together  into 
definite  experiences.  The  piecemeal  sensations  are  worked 
into  shape  by  a  number  of  mental  processes:  impression, 
suggestion,  revival,  attention,  composition,  and  discrimina- 
tion. As  a  result  of  this  working  over  we  have  a  number  of 
different  sorts  of  experience  —  perception,  memory,  etc.  — 
which  will  be  discussed  in  the  following  chapters. 

In  addition  to  our  conscious  or  personal  experiences  there 
are  certain  brain  effects  of  which  we  are  not  aware.  These 
are  called  subconscious  experiences.  They  are  either  (1) 
subliminal,  that  is,  too  faint  to  be  noticed;  or  (2)  subordinate, 
that  is,  they  occur  on  a  lower  brain  level  and  not  in  the 
cortex.  Our  conscious  experiences  are  also  subject  to  changes 
of  vividness  due  to  the  condition  of  our  receptors:  hyperes- 
thesia means  a  high  degree  of  consciousness;  undersensitivity 
(hypesthesia)  means  a  faint  degree  of  experience,  the  limit 
being  anesthesia,  or  entire  absence  of  sensation. 

With  practice  we  can  learn  to  observe  our  own  experiences 
and  note  their  characteristics.  This  method  of  studying 
mental  facts  is  called  self-observation  or  introspection. 


142  CONSCIOUS  LIFE  [ch.  vi 

Practical  Exercises: 

28.  Examine  your  experience  in  trying  to  read  when  an  interesting  con- 
versation is  going  on  in  the  room.  Describe  the  changes  of  attention 
from  one  group  of  impressions  to  the  other,  and  the  marginal  elements 
of  the  experience. 

29.  Report  your  experiences  in  trying  to  listen  to  a  lecture  when  you  are 
very  sleepy.  Note  especially  any  fluctuations  of  attention,  diffusion 
of  attention,  snatches  of  anesthesia. 

30.  Describe  some  recent  experience  in  which  you  have  worked  out  a 
problem  subconsciously  or  performed  some  rather  complex  act  sub- 
consciously. 

81.  Describe  any  notable  experience  of  anesthesia  or  hyperesthesia  in 
your  recent  life. 

32.  Examine  one  of  your  well-formed  habits  (e.g.,  dressing,  eating  with 
table  implements,  taking  a  customary  walk) ;  what  factors  seem  to  be 
(1)  conscious,  (2)  subconscious,  (3)  absolutely  unconscious? 

References: 
On  attention:  W.  B.  Pillsbury,  Attention. 
On  subconsciousness:  M.  Prince,  The  Unconscious. 
On  psychoana^sis:  S.  Freud,  Psychopathology  qf  Everyday  Life. 


CHAPTER  Vn 
PERCEPTION 

Nature  of  Perception.  —  Perceptions  are  experiences  due  to 
direct  impressions  from  the  external  senses.  This  is  slightly 
narrower  than  the  ordinary  use  of  the  term.  It  is  all  right  in 
oflfhand  conversation  to  speak  of  *  perceiving  a  pain '  or 
*  perceiving  the  truth.'  But  when  we  study  mental  states 
systematically,  it  is  important  to  call  different  sorts  of  experi- 
ences by  different  names:  We  'perceive  what  is  outside  the 
body,  we  feel  what  takes  place  within  the  body,  and  we 
believe  the  truth  of  propositions. 

Perception  is  the  grouping  together  of  various  external 
sensations^  into  a  single,  united  experience.  Your  percep- 
tion of  this  book  involves  putting  together  a  large  number  of 
sensations  obtained  through  your  eye  and  optic  nerve.  Each 
letter  on  the  page  stimulates  your  retina  at  some  point  and 
starts  a  nerve  impulse  along  some  of  the  optic  nerve  fibers 
toward  your  brain.  Hundreds  of  these  impulses  reach  the 
visual  center  at  the  same  time  and  give  separate  sensations. 
In  the  center  the  separate  impulses  are  brought  together  by 
the  nervous  process  of  collection,  and  the  complex  impulse 
which  ensues  arouses  a  complex  experience  of  the  whole 
printed  page.  The  combining  process  is  called  perception; 
the  experience  is  a  perception. 

Our  perceptions  correspond  very  closely  to  the  objects 
which  cause  them.  If  your  eyesight  is  good,  the  shape  and 
markings  of  the  perceived  book  are  very  similar  to  the  shape 
and  markings  of  the  real  book  which  lies  beyond  your  eyes 

'  An  'external  sensation'  is  a  sensation  coming  from  one  of  the  'exteraal 
senses,'  such  as  sight  (see  Table  I,  p.  58).  The  stimulus  is  outside  our  body. 
The  expression  external  sensation  is  short  for  externally  stimulated  sensation. 


144 


PERCEPTION 


[cH.  vn 


Fig,  52.  —  Filled-in 
Perception 

Hold  the  book  at  a  distance  and  the 
outline  of  the  letters  appears  complete. 
The  missing  lines  are  supplied  in  per- 
ception. 


and  furnishes  the  visual  stimuli.  This  is  true  also  of  per- 
ception by  touch.  We  perceive  the  roughness  of  sandpaper 
or  of  a  gravel  walk.  Our  experiences  resemble  the  situation 
in  the  world  outside  our  body. 

The  correspondence  between  perception  and  reality  is  not 
always  perfect.  We  often  have  illusions  in  perception,  — 
that  is,  things  do  not  always  appear  as  they  really  are.  Some 
of  these  illusions  are  very  striking.  In  Fig.  52  we  see  per- 
fectly clearly  the  entire  outline 
of  the  letters;  we  see  hues  where 
there  are  no  lines  at  all. 

The  lack  of  complete  harmony 
between  the  perception  and  the 
thing  perceived  is  not  remark- 
able when  we  consider  the  chain 
of  processes  involved  —  light 
waves,  retinal  activity,  nerve 
impulses,  central  collection,  and 
other  operations.  It  is  like  transmitting  a  telegram.  You 
write  out  the  message  in  pencil,  the  telegrapher  clicks  it  off, 
the  receiving  operator  hears  a  succession  of  dots  and  dashes 
and  typewrites  the  words  in  Roman  letters.  It  is  really 
surprising  that  more  mistakes  do  not  occur  in  perception. 
The  exactness  with  which  our  experiences  correspond  to 
reality  is  evidence  of  the  high  precision  of  our  receptors  and 
nervous  system. 

Often  our  perceptions  are  more  like  the  real  object  than  the 
sensations  which  compose  the  experience  would  lead  us  to 
expect.  For  instance,  if  we  tilt  a  book  at  an  angle  (like  the 
book  shown  in  Fig.  56  ^  the  four  corners  still  appear  as 
rectangles,  though  the  sensations  taken  by  themselves  would 
make  the  page  look  diamond-shaped.  The  reason  why  the 
comers  look  rectangular  is  that  our  perceptions  include  not 
merely  sensations  but  memories  of  other  books  we  have  seen 

ip.  151. 


CH.  vn]  NATURE  OF  PERCEPTION 


145 


FlO.  53.  —  IlXTTSION  OF  THE 

Crosses 

The  rectangular  crosa-lines  either  look 
oblique  or  seem  to  swing  into  the  paper ; 
the  oblique  cross-lines  look  rectangular. 


and  handled  in  the  past.  These  memory  elements  combine 
with  the  present  sensations,  and  since  all  books  are  made  with 
square  comers  the  resulting  per- 
ception takes  that  form.  This 
tendency  to  interpret  accordijog^ 
to^ast  experience  is  so  strong 
that  in  Fig.  53  the  rectangular 
cross-lines  look  tilted,  and  the 
tilted  Unes  look  rectangular. 

There  are  certain  errors  in 
perception  due  to  defects  of  the 
receptors.  If  you  are  astig- 
matic, everything  looks  some- 
what distorted;  if  you  are  near- 
sighted, objects  at  a  distance 
are  blurred.  You  are  quite 
aware  in  such  cases  that  your 
perception  is  faulty.  But  there 
are  also  errors  in  perception  which  one  does  not  appreciate. 
Certain  objects  are  colored  with  ultrarviolet  or  infra-red 
light;  we  cannot  see  these  colors  because  the  retina  does  not 
receive  such  rays.  Ordinarily  we  see  nothing  of  what  is 
going  on  inside  our  own  body;  but  the  X-ray  penetrates 
the  tissues,  and  if  our  eyes  were  sensitive  to  the  X-ray,  we 
could  see  through  a  human  body  almost  as  readily  as 
through  a  glass  window.  There  are  sounds  in  the  world 
about  us  which  perhaps  an  insect  can  perceive  plainly,  but 
which  man  cannot  hear.  The  dog's  perception  of  his  master 
by  smell  is  incomprehensible  to  the  human  nose.  We  do 
not  perceive  the  earth's  magnetic  current  directly  at  all. 

It  follows  that  our  perceptions  of  the  world  about  us  are 
not  exactly  Uke  the  real  world.  We  are  Umited  to  material 
that  our  receptors  can  take  in.  So  far  as  we  can  perceive, 
we  generally  perceive  things  in  their  real  relations ;  we  inter- 
pret our  sensations  truly,  except  for  certain  iUusions  based  on 


146  PERCEPTION  [ch.  vn 

habit.  The  piecing  together  and  interpretation  of  sensations 
is  due  to  the  mental  processes  of  composition,  attention,  etc. 
(ch.  vi).  It  takes  place  ajter  the  nerve  impulses  have 
reached  the  brain  centers. 

There  are  quite  a  number  of  different  ways  of  working  over 
the  sensory  material  in  perception.  We  shall  discuss  them  in 
the  following  order: 

Discrimmation 
Perception  of  surfaces 
Perception  of  depth 
Perception  of  objects 
Perception  of  time  and  events 

a.  T>^syriB]i"fltinn  |  Wfiher*R  Law.  —  Discrimination  of  two 
things  does  not  always  mean  that  we  consciously  perceive 
their  difference.  A  very  small  difference  between  two  sensa- 
tions may  lead  to  subconscious  discrimination.  When  we 
compare  two  lifted  cylinders  that  are  nearly  equal  in  weight 
there  is  some  discrimination,  as  shown  by  the  fact  that  con- 
siderably more  than  half  our  judgments  are  correct,  though 
they  seem  mere  guesses.^  Our  automatic  balancing  move- 
ments when  we  ride  a  bicycle  are  based  on  subconscious  dis- 
crimination. 

Conscious  discrimination  occurs  when  the  nerve  impulses 
reach  the  higher  brain  centers  in  the  cortex.  We  perceive  a 
difference  of  quality  or  intensity  between  two  sensations 
when  the  two  sensory  impulses  are  brought  together  in  a 
perception  center  of  the  brain,  and  the  central  impulse  is  dis- 
tributed on  the  basis  of  this  difference.  Suppose  you  lift 
two  cylinders  which  are  noticeably  different  in  weight.  The 
two  sensations  are  different,  and  this  difference  starts  a  motor 
impulse  in  the  proper  channel,  so  that  you  point  to  the 
heavier,  or  say,  "  the  first  is  heavier,"  or  respond  in  some 
other  discriminative  way.  You  react  discriminatively  be- 
cause you  have  arranged  to  do  so  beforehand,  and  because 
^  See  ch.  vi,  p.  187. 


cm.  vn]  WEBER'S  LAW  147 

the  motor  paths  from  the  brain  centers  are  prepared  to  send 
the  impulses  down  to  the  motor  organs.  But  whether  you 
will  point  to  the  first  or  to  the  second  cylinder  is  deter- 
mined by  the  difference  between  the  two  sensations  and  by 
the  central  process  of  discrimination. 

Considerable  work  has  been  done  in  the  psychological 
laboratory  on  the  perception  of  very  small  differences. 
There  is  no  special  problem  in  distinguishing  large  differences: 
when  a  thick  cloud  passes  over  the  sun,  we  notice  the  darken- 
ing effect  at  once.  But  if  we  are  reading  in  the  late  afternoon 
it  often  happens  that  we  do  not  notice  the  growing  dusk  till 
suddenly  the  strain  of  reading  brings  us  to  a  reaUzation  that 
the  light  has  greatly  diminished. 

How  much  difference  must  there  be  between  two  things  in 
order  that  we  may  be  able  to  consciously  distinguish  them? 
This  is  an  important  problem  in  psychology,  since  it  deter- 
mines the  number  of  different  impressions  we  are  capable  of 
experiencing.  In  the  laboratory  this  is  investigated  by 
taking  two  stimuli  of  the  same  sort  and  varying  the  inten- 
sity of  one  (the  other  remaining  constant)  till  we  no  longer 
observe  any  difference  between  the  two.  Or,  starting  with  the 
two  alike,  we  gradually  vary  the  intensity  of  one  till  it  is  just 
observably  different  from  the  other.  This  can  readily  be  done 
with  any  of  the  external  senses;  we  can  compare  the  bright- 
ness of  two  lights,  the  loudness  of  noises,  the  intensity  of 
tastes  and  odors,  the  heaviness  of  pressure  or  lifting.^ 

Experimental  investigations  show  that  the  intensity  of  a 
stimulus  must  be  increased  by  a  certain  proportion  of  itself 
in  order  to  give  a  just  observably  different  sensation.  For 
example,  whatever  the  intensity  of  a  light,  it  must  be  in- 
creased by  l/lOO  of  itself  to  appear  brighter;  pressure  on  the 
skin  (without  lifting)  must  be  increased  by  l/20  to  be  dis- 
tinguished; a  hfted  weight  must  be  l/40  heavier  in  order  to 
be  noticeably  heavier.     This  law  of  discrimination  was  first 

*  The  muscle  sense  belongs  among  the  eternal  senses  in  this  respect. 


14d 


PERCEPTION 


[CH.  VII 


S 


formulated  by  E.  H.  Weber  in  1834,  on  the  basis  of  his  own 
experiments,  and  is  called  Weber's  Law.  Weber's  Law  may 
be  stated  in  a  simple  form:  Sensations  increase  in  arithmetical 
progression  as  the  stimuli  increase  in  geometrical  progression. 
Weber's  Law  as  applied  to  sound  intensity  is  represented 
by  the  curve  shown  in  Fig.  54.    Here  the  fraction  of  increase 

is  1/3.  For  pressure  and  bright- 
ness the  curve  is  of  the  same 
form,  but  it  is  much  flatter: 
each  step  requires  less  increase 
in  these  senses  than  in  hearing. 
When  two  stimuli  are  nearly 
alike  our  discrimination  is  often 
influenced  by  inattention,  dis- 
tracting stimuli,  and  other  fac- 
tors; so  that  a  large  number  of 
experiments  are  needed  to  de- 
termine the  fraction  of  increase 
exactly.  But  the  fundamental 
principle  can  easily  be  verified. 
Compare  the  difference  of 
brightness  in  a  darkroom  lighted 
first  with  one  candle,  then  with 
two;  now  compare  daylight, 
with  daylight  increased  by 
one  candle.  In  the  darkroom 
comparison  the  difference  apn 
pears  very  great,  in  the  daylight 
it  is  not  noticeable.  The  differ- 
ence between  3  oz.  and  4  oz.  is 
very  noticeable,  while  the  difference  between  4  lb.  and  4  lb. 
1  oz.  is  imperceptible.  It  is  always  the  relative  difference  — 
not  the  absoliUe  difference  —  that  we  distinguish. 

The  fraction  of  least  observable  difference  is  called  the 
Weber  Constant.     The  constant  for  various  senses  is  shown 


J 


11 


"       Si    S>  it  H  it    f   »r  5a  it  in  Su   Sn 

Ro.  64.  —  Curve  of  Weber's 
Law 

Form  of  tbe  curve  for  intensity  of 
sound;  the  Weber  fraction  is  1/3.  Just 
observable  increases  of  sensation  are  in- 
dicated by  equal  distances  along  the  X 
axis  at  points  Si,  Sj,  S3,  etc.  Correspond- 
ing values  of  stimuli  are  represented  by 
the  lines  Si  —  R],  Sj  —  Rj,  etc.  For  pres- 
sure the  Weber  fraction  is  1/20;  the  curve 
is  much  flatter. 


CH.  VII  ] 


WEBER'S  LAW 


149 


in  Table  VII.  Weber's  Law  holds  to  some  extent  for  dis- 
crimination of  duration  and  size  as  well  as  intensity.  It  does 
not  hold  for  least  observable  differences  in  qualities,  such  as 
color  hues  and  auditory  tones. 

Table  VII. —  Values  of  the  Webeb  Constant 


Sensation 

L.P.D.  IrUensity 

Individual  range 

Visual  (light) 

0.01 

0.33i 

0.15 

0.25 

0.25 

0.05 

0.036 

0,036 

0.025 

0.015  to  0.005 

Auditory  (noise)   

"      (tones) 

Olfactory 

0.20    to  0.125 
0.33    to  0.25 

Gustatory 

0.33    to  0.25 

Tactile 

0.10   to  0.033 

Warmth 

Cold 

Kinesthetic 

0.05    to  0.013 

Each  fraction  denotes  the  proporHon  of  the  original  stimulus  which  must  be  added  to  it  in 
order  that  the  sensation  may  be  just  noticeably  greater, 

b.  Perception  of  Surfaces.  —  The  perception  of  space  rela- 
tions includes  two  very  different  processes.  One  is  perception 
of  the  size  and  shape  of  objects  that  we  see  or  touch.  The  other 
is  the  perception  of  distance  of  objects  from  our  body.  The 
former  is  called  surface  perception,  the  other  is  depth  per- 
ception. 

Surface  perception  is  much  the  simpler  process.  Objects 
which  we  see,  stimulate  a  great  number  of  rods  and  cones  in 
the  retina,  and  the  things  which  touch  our  skin  stimulate 
many  different  touch  receptors.  When  the  separate  visual 
(or  tactile)  impressions  from  all  parts  of  the  object  are  com- 
bined together  in  the  brain  centers  we  get  a  perception  of 
something  spread  out  before  us.  The  question  is,  how  we 
come  to  perceive  the  various  parts  of  any  object  in  the  same 
relations  to  one  another  that  they  really  bear.  This  really 
involves  three  distinct  problems.  Take,  for  instance,  touch 
perception  [Fig.  55]: 


150 


PERCEPTION 


[cH.  vn 


(1)  How  do  we  distinguish  two  points  A  and  B  on  the  skin  at  all?  Why  do 
they  not  fuse,  like  sounds? 

(2)  How  do  we  p)erceive  that  a  given  point  A  on  the  skin  is  farther  distant 
from  C  than  from  B? 

(3)  How  do  we  perceive  that  C  and  X  are  in  different  directions  from  A? 


The  same  three  questions  come  up  in  visual  perception: 
How  do  we  distinguish  different  points,  perceive  their  dis- 
tance apart,  and  appreciate  direction?  Sight  and  touch  are 
the  two  chief  sources  of  surface  perception. 

(1)  First  as  to  discrimin^wxLJi^..djfferent  points.  This  is 
due  tosTighl  diller^IlW!y  Inthe  receptors  themselves.     Each 

rod  and  cone  in  the  retina,  each 
touch  corpuscle  in  the  skin, 
is  slightly  different  from  every 
other  and  gives  slightly  differ- 
ent sensations.  These  slight 
differences  are  local  signs  (that 
is,  indications  of  locality)  which 
enable  us  to  distinguish  one 
point  from  another.  We  can 
think  of  them  as  the  *  personal 
touch '  which  each  receptor 
gives  to  its  stimuli,  just  as  the 
timbre  of  each  man's  voice  has 
its  own  individuality,  which 
enables  us  to  recognize  who  it 
is  that  is  talking  regardless  of 
what  he  is  saying. 

(2)  The  second  question  is 
how  we  come  to  perceive  cor- 
rectly the  size  of  objects  and 
their  distance  apart.  Two  fac- 
tors assist  us  in  getting  our  clue 
to  surface  distances,  (i)  When  objects  move  over  the  body  or 
before  the  eye,  or  the  skin  or  eye  is  moved  over  stationary 


FiQ.  65.  — Space  Pehception 
IN  Touch 

Arrows  indicate  direction  in  which 
•timulus  moves  over  the  skin.  (See  dis- 
cussion in  text.) 


CH.  vii]  SURFACE  PERCEPTION  151 

objects,  any  given  point  on  the  object  stimulates  a  number 
of  receptors  in  regular  order.  On  the  skin  the  points  ABC... 
K  L  [Fig.  55]  are  stimulated  in  succession,  or  else  some  other 
series  A  W  X  Y  Z  L.     We  never  get  the  sensations  in  a 


Direction  gf  Eye  movemerit 

Fig.  56.  —  Visual  Space  Pebception 

Dotted  lines  show  paths  of  light  waves  from  a  point  P  on  the  book-cover  toward  the  eye, 
first  spreading  out,  then  brought  together  by  the  lens  and  focused  at  A  on  the  retina.  When 
the  eye  moves  counter-clockwise  (in  direction  of  lower  arrow),  the  picture  of  P  on  the  retina 
moves  clockwise  (left-hand  arrow)  from  A  to  B,  C,  D.     (See  discussion  in  text.) 

random,  jumbly  order,  A  K  B  L  C.  The  same  is  true  in 
sight.  The  eye  moves  regularly;  any  given  point  (say,  the 
letter  P  in  Fig.  56)  stimulates  the  rods  and  cones  of  the  retina 
in  some  regular  order,  such  as  A  B  C  D,  never  in  random 
order. 

This  means  that  any  given  point  K  on  the  skin  or  D  on 
the  retina,  which  is  situated  far  from  the  starting-point  A,  is 
not  stimulated  by  a  given  object  immediately  after  A,  but 
only  after  a  number  of  other  points  have  been  stimulated. 
The  same  series  ABCKorABCD  occurs  over  and  over 
again,  and  this  enables  us  to  appreciate  that  B  and  C  are 
nearer  A  than  are  any  of  the  points  which  are  stimulated 
afterwards. 

(ii)  The  muscle  sense  aids  greatly  in  building  up  our  j)er- 
ception  of  size.  When  we  move  the  hand  or  the  eye  we  get 
muscle  sensations.  If  the  movement  is  quick,  the  muscle 
sensations  are  more  intense;  the  unusual  muscular  exertion 
informs  us  that  the  starting  and  stopping  points  are  farther 
distant  than  the  mere  time  would  indicate.     If  the  move- 


15«  PERCEPTION  fcH.  vii 

ment  is  very  slow,  the  muscle  sensations  are  faint  and  the 
distance  is  perceived  to  be  small. 

Om*  perception  of  the  length  of  a  line  or  the  size  of  an 
object,  then,  is  due  to  these  two  factors :  (i)  the  orderly  suc- 
cession of  points  on  the  skin  or  retina,  with  their  distinguish- 
ing local  signs,  and  (ii)  the  intensity  of  the  muscle  sensations 
which  accompany  the  movements  of  our  limbs  or  eyes. 

(3)  Finally  the  question  arises,  how  we  come  to  appreciate 
difference  in  direction.  Muscle  sensations  furnish  the  chief 
information  regarding  the  direction  of  lines  and  their  curva- 
ture, which  is  an  important  element  in  surface  perception. 
In  Fig.  55  the  points  C  and  X  are  equally  distant  from  A. 
But  the  hand  moves  differently  in  the  two  cases,  so  that  the 
muscle  sensations  when  we  move  from  A  to  C  are  different 
from  the  muscle  sensations  which  accompany  a  movement 
from  A  to  X. 

In  sight  this  factor  is  even  more  evident.  When  we  turn 
the  eyes  upward  the  superior  muscles  do  most  of  the  con- 
tracting; when  we  turn  them  toward  the  right  it  is  one  of 
the  horizontal  muscles  of  each  eye.  The  muscle  sensations 
in  the  two  cases  are  different,  and  this  difference  of  sensation 
enables  us  to  distinguish  the  direction  of  the  two  movements 
readily.  For  diagonal  movements  one  horizontal  and  one 
vertical  muscle  come  into  play;  we  perceive  the  direction 
according  to  the  proportion  of  sensation  from  each  muscle. 

To  sum  up,  surface  perception  includes  three  independent 
mental  acts:  (1)  We  distinguish  between  different  points  and 
parts  of  objects  by  means  of  heal  signs.  (2)  We  perceive 
their  distance  apart  by  means  of  the  orderly  succession  of  local 
signs  and  by  the  varying  intensity  of  the  accompanying  muscle 
sensations.  (3)  We  appreciate  differences  of  direction  by 
means  of  the  different  muscle  sensations  which  accompany 
movements  of  the  eye,  hand,  or  other  members.  When  we 
look  at  things  or  touch  them,  we  get  these  clues  in  addition 
to  the  touch  and  visual  sensations.    They  give  us  information 


CH.  vn]  SURFACE  PERCEPTION  153 

which  enables  us  to  perceive  objects  as  spread  out  in  space 
before  us, 

c.  Visual  Depth  (Projection  and  Perspective).  —  The  dis- 
tant senses  give  us  information  about  things  that  are  more 
or  less  distant  from  the  body.  The  stimuli  come  in  contact 
with  the  receptors,  but  the  objects  themselves  do  not. 
When  we  see  and  smell  a  rose,  stimuli  from  the  rose  aflFect 
our  visual  and  olfactory  receptors;  but  the  rose  remains  out 
there  on  the  stalk,  some  distance  off.  In  such  cases  we  pei> 
ceive  the  object  "  where  it  is  "  —  the  rose  does  not  seem  to  be 
in  contact  with  our  eyes  or  inside  our  nostrils. 

How  is  it  that  we  see  the  rose  projected  out  at  a  distance 
from  the  eye,  although  our  sensations  are  due  to  stimuli  on 
the  retina?  Perception  of  depth  (that  is,  distance  straight 
away  from  the  eye  toward  the  horizon)  is  not  due  to  local 
signs;  for  the  stimuli  from  all  distances  in  the  same  line  from 
the  eye  strike  the  same  point  on  the  retina  and  bear  the  same 
local  sign.     The  same  is  true  of  hearing  and  smell. 

Sight  is  far  more  developed  in  its  space  relations  than  the 
other  senses.  We  are  able  to  distinguish  very  accurately  the 
distance  of  objects  from  the  eye.  We  see  a  statue  '  in  per- 
spective '  —  that  is,  the  perception  rounds  out  toward  us  in 
curves  like  the  real  statue.  What  factors  in  the  sensation 
enable  us  to  project  our  visual  perceptions  in  this  way? 

Depth  perception  in  sight  is  due  to  a  combination  of  cer- 
tain non-visual  information  with  the  visual  sensations,  just 
as  surface  perception  is  due  to  the  combination  of  local  signs 
and  muscle  sensations  with  the  sensations  of  sight.  Some  of 
the  clues  for  perceiving  depth  accompany  the  visual  sensa- 
tions from  each  eye  separately;  we  get  them  as  readily  when 
one  eye  is  closed.  Other  clues  are  due  to  the  two  eyes  work- 
ing together.  There  are  six  uniocular,  and  two  binocular 
factors. 

(1)  Accommodation  Sensations:  The  lens  of  the  eye 
bulges  out  when  we  look  at  objects  close  by,  and  flattens  when 


154  PERCEPTION  [ch.  vn 

we  look  at  distant  objects.'  Muscle  sensations  accompany 
these  changes  of  the  accommodation  muscle;  the  sensations 
vary  with  the  amount  of  muscular  contraction.  These 
accommodation  sensations  are  an  important  clue  for  percep- 
tion of  depth  or  distance  away  from  the  eye.  When  we  focus 
the  eye  for  a  given  distance  we  get  a  certain  muscle  sensation 
which  tells  us  how  far  off  we  are  focusing. 

Accommodation  sensations  assist  us  only  in  determining  a 
limited  range  of  depth  distances.  The  lens  of  the  normal 
human  eye  is  completely  relaxed  when  we  focus  for  about  6 
to  10  meters  (20  to  33  feet).  There  is  also  a  near-by  limit, 
normally  about  10  cm.  (4  inches);  we  cannot  squeeze  the 
lens  suflSciently  to  get  a  clear  picture  of  nearer  objects. 
Within  these  limits  the  changes  of  accommodation  sensations 
furnish  clues  which  enable  us  to  perceive  rather  exactly  the 
depth  of  objects.  For  perception  of  greater  distances  other 
factors  are  needed. 

(2)  Distinctness:  Owing  to  the  dust  in  the  atmosphere, 
objects  at  a  distance  are  not  so  distinct  as  those  near  by. 
Objects  seem  close  to  us  if  their  outlines  are  sfiarp  and  their 
details  are  clearly  marked  off;  they  appear  farther  off  as  the 
outlines  and  details  grow  more  vague.  Distinctness  is  an 
important  clue  for  depth  perception,  but  it  often  gives  mis- 
leading information.  We  misinterpret  distances  when  the 
atmosphere  is  unusually  clear  or  unusually  dense.  In  Colo- 
rado mountains  thirty  or  forty  miles  away  seem  only  a  half- 
hour  walk.  On  a  misty  day  objects  look  larger  and  farther 
away  than  they  really  are.  These  mistakes  of  perception  are 
called  illusions. 

(3)  Shading  :  When  light  strikes  the  human  face  from  the 
right,  the  nose  casts  a  shadow  on  the  left  cheek,  the  mouth  is 
in  shadow,  etc.  Shading  is  a  clue  to  the  different  distance  of 
various  parts  of  an  object  from  the  observer.     This  factor 

^  Stand  close  to  some  one,  at  hia  side,  and  observe  the  changes  as  he  looks 
near  by  and  far  away. 


CH.  vii]  DEPTH  AND  PROJECTION  155 

gives  the  finest  of  all  depth  distinctions.  It  enables  us  to  see 
objects  in  perspective  and  in  relief.  So  powerful  is  its  in- 
fluence that  we  tend  to  interpret  the  flat  surface  of  a  painting 
or  photograph  in  terms  of  depth.  Some  objects  in  the  pic- 
ture stand  out  and  others  recede  back  from  the  canvas  or 
paper.  In  the  theater,  we  perceive  a  cottage  in  the  back- 
ground at  least  two  or  three  miles  away,  though  we  know 
perfectly  well  that  it  is  really  painted  on  a  stage  curtain. 
The  illusion  is  irresistible  if  the  curtain  is  seen  through  a  glass 
window;  the  glass  makes  the  imperfections  of  the  painted 
curtain  less  apparent. 

(4)  Superposition  :  If  two  objects  lie  in  the  same  straight 
line,  the  nearer  one  will  hide  part  of  the  farther  one.  When 
we  see  the  outline  of  a  house  broken  by  a  tree,  the  house 
looks  farther  away  than  the  tree.  This  effect,  called  super- 
position, is  of  great  use  in  perceiving  the  relative  distance  of 
different  objects  from  us.  The  illusion  of  perspective  in 
photographs  and  paintings  depends  largely  on  this  factor. 

(5)  Size  and  Shape  of  Familiar  Objects:  Many  of  the 
familiar  creatures  and  objects  around  us  are  of  a  '  standard 
size,'  with  only  sUght  variations.  Grown-up  human  beings 
vary  in  height  only  a  few  inches  from  the  average.  When  we 
see  a  man,  the  size  of  the  impression  on  our  retina  is  a  clue  to 
his  distance.  If  the  retinal  picture  is  small  the  man  looks 
far  away,  if  it  is  large  he  looks-  near  by.  Houses  differ 
considerably  in  size,  but  the  windows  and  the  height  of 
the  stories  are  fairly  uniform;  we  appreciate  the  distance 
of  a  house  by  means  of  this  factor.  And  so  of  any  familiar 
thing. 

This  factor  may  give  rise  to  illusions.  A  miniature  house 
on  the  stage  is  perceived  as  a  full-sized  house  in  the  distance. 

The  shape  of  a  familiar  object  also  gives  us  a  clue  to  its 
position.  Book  covers  are  usually  rectangular;  when  we  see 
a  book  lying  before  us  whose  cover  has  two  acute  and  two 
obtuse  angles  we  project  one  of  the  acute  comers  farther 


156  PERCEPTION  [ch.  vii 

away  from  us  than  the  other.     [Fig.  56.]     In  paintings  and 
pictures  the  perspective  effect  is  enhanced  by  this  factor. 

(6)  Relative  Motion:  When  we  look  out  of  the  window 
of  a  moving  train,  objects  near  at  hand  pass  by  much  more 
rapidly  than  distant  objects.  If  we  are  standing  still  and 
move  the  head  to  right  and  left  the  same  thing  happens.  In 
either  case  we  get  a  clue  of  the  distance  of  various  objects 
from  their  relative  rate  of  motion  across  the  field  of  vision. 
For  one-eyed  persons  this  is  the  most  important  factor  in 
giving  perspective  to  the  landscape. 

(7)  Convergence:  Focusing  the  two  eyes  upon  a  single 
point  is  called  convergence.  When  we  look  first  at  an  object 
some  distance  off  and  then  at  a  nearer  object  in  the  same 
direction,  the  eyes  do  not  turn  both  together,  as  in  ordinary 


-     N  f 


Fig.  57.  —  Convergence  of  the  Eyes 

When  the  eyes  are  fixed  on  a  distant  point  F  both  pupils  are  shgbtly  converged 
toward  the  nose,  as  shown  in  the  upper  figure.  When  we  look  from  F  to  a  point 
N  near  by  in  the  same  direction,  both  eyes  turn  in  toward  the  nose  (converge 
more),  as  shown  in  the  lower  figure. 

movements.  Either  one  eye  remains  fixed  and  the  other 
turns  slightly  inward  (toward  the  nose);  or  else  both  turn 
inward  —  they  converge.  [Fig.  57.]  Since  the  eye  move- 
ments in  convergence  are  different  from  ordinary  eye  move- 


CH.  vii]  DEPTH  AND  PROJECTION  157 

merits,  the  accompanying  muscle  sensations  are  different. 
They  give  us  a  clue  as  to  the  distance  from  us  of  the  point 
upon  which  the  eyes  are  converged.  This  factor  supplements 
the  various  uniocular  indications  described  above;  but  its 
value  is  limited  to  distances  of  not  more  than  one  hundred 
feet;  beyond  this  there  is  practically  no  change  in  the  angle 
of  convergence. 

(8)  Binocular  Differences:  If  you  hold  a  piece  of  card- 
board between  the  two  eyes  with  one  edge  toward  you,  the 
left  eye  sees  only  one  side  of  the  cardboard  while  the  right 
eye  sees  the  other;  your  two  visual  fields  are  different.  If 
you  hold  a  ball  near  the  eyes,  the  right  eye  sees  a  little  farther 
around  it  to  the  right  than  the  left  eye.  Any  rounded  object 
which  is  near  your  body  presents  a  slightly  different  picture 
to  the  two  eyes.  These  two  different  pictures  do  not  clash 
as  one  would  think;  they  combine  into  a  single  definite  per- 
ception, so  that  the  object  '  stands  out  in  relief.'  It  looks 
rounded  out  and  solid. 

The  combination  of  binocular  pictures  may  be  studied  by 
means  of  the  stereoscope,  [Fig,  58.]  In  the  holder  of  the 
stereoscope,  several  inches  from  the  eyes,  is  placed  a  card  with 
two  pictures.  The  pictures  are  neariy  alike,  but  not  quite; 
the  left  picture  is  the  way  a  solid  object  or  scene  would  look 
to  the  left  eye  if  it  were  some  distance  off  —  the  right  is  the 
scene  as  it  would  appear  to  the  right  eye.  By  means  of 
prism  lenses  the  two  pictures  are  brought  together  in  the 
middle  of  the  field  of  vision.  One  is  seen  by  the  right  eye 
and  the  other  by  the  left,  but  we  see  only  a  single  picture. 
Examine  a  pair  of  stereoscopic  photographs  without  the 
instrument  and  notice  how  different  some  of  the  details  are. 
Yet  when  the  two  are  combined  in  a  stereoscope  they  give 
one  distinct  picture,  just  as  we  would  see  a  similar  scene  with 

t^  two  cy^jx^^ 

[ow  xnS^Clues  dre  useoT —  Of  tlie  various  sorts  of  clues 
that  enable  us  to  see  at  a  distance,  only  one  (binocular  differ- 


158 


PERCEPTION 


[cH.  vn 


ence)  is  really  a  visual  sensation.  Some  of  the  clues  are 
muscle  sensations  that  occur  at  the  same  time  as  the  visual 
sensations  and  combine  with  them;  and  some  are  not  even 
sensations,  —  they  are  memories  of  past  sensations.   The  size 


Fig.  58.  —  Stereoscope 

Above,  a  stereoscope.  Left  eye  looks  through  A  at  left-hand  picture  of  card  G  in  card  -holder 
F;  right  eye  looks  through  B  at  right-hand  picture.  Prisms  C,  C  bring  the  two  pictures  to- 
gether into  a  single  view  in  the  middle  of  tlie  visual  field.  E  =  rod  for  sliding  the  holder  to 
and  from  the  eyes.    D  =  handle  to  hold  stereoscope. 

Below,  a  card  with  pair  of  stereoscopic  pictures.  Looking  at  the  card  through  the  stereo- 
scope we  see  a  single  picture  of  a  pyramid.  (The  two  pictures  in  the^upper  card  G  also  com- 
bine into  a  solid-looking  picture.) 

of  familiar  objects  is  a  memory  of  many  former  perceptions 
of  these  objects.  When  we  perceive  a  tilted  book  as  having 
right-angled  corners,  the  experience  involves  previous  per->- 
ceptions  of  books  in  many  tilted  positions.  The  memory 
clues  and  muscle-sense  clues  are  combined  with  the  visual 
sensations  derived  from  the  objects  and  the  total  effect  is  a 
perception  of  things  at  a  distance.  The  scene  is  projected. 
It  would  be  wrong  to  say  that  we  first  see  things  flat  and 


CH.  vii]  DEPTH  AND  PROJECTION  159 

then  correct  this  impression.  The  projective  process  is 
immediate  —  it  is  not  an  inference.  We  perceive  the  size  and 
tilt  and  depth  of  things  at  once.  This  is  proved  by  experi- 
ments with  instantaneous  or  very  short  exposures.' 

It  is  difficult  to  understand  how  we  come  to  have  one  single 
perception,  and  not  two,  when  each  of  the  eyes  has  a  retinal 
picture  of  the  entire  field.  This  is  partly  explained  by  the 
course  of  the  optic  nerve.  At  the  optic  chiasm  [Fig.  27  ^]  the 
fibers  from  the  inner  (nasal)  half  of  each  retina  cross  to  the 
opposite  side  of  the  brain;  those  from  the  outer  half  do  not. 
The  fibers  from  the  left  half  of  each  retina  go  to  the  left  side 
of  the  brain,  those  from  the  right  half  go  to  the  right  side; 
so  that  two  similar  stimuli  from  corresponding  points  in  the 
two  retinas  arrive  at  neighboring  points  in  the  visual  center 
of  the  brain  at  the  same  time.  Just  how  these  pairs  of  cor- 
responding central  points  are  connected  is  not  known.  It  is 
a  case  of  fusion,  and  is  similar  to  the  fusion  of  identical  soimd 
impressions  from  the  two  ears. 

It  is  also  puzzling  to  understand  how  we  see  objects  "  oflf 
at  a  distance  "  when  the  perception  process  actually  takes 
place  in  the  brain.  This  much  can  be  said  about  it:  Pro- 
jection is  one  of  many  ways  in  which  the  raw  material  of 
experience  is  worked  over  and  transformed.  A  *  projected 
out '  quality  is  added  to  the  various  sensations  that  enter 
into  our  experience  of  distant  objects,  just  as  a  '  spread-out ' 
quality  is  added  to  the  experience  of  visual  surface.  Our 
projection  of  visual  experiences  means  only  that  we  project 
most  of  these  visual  pictures  beyond  the  visual  'picture  of  our 
oum  body,  which  forms  part  of  our  visual  world. 

Projection  in  Other  Senses.  —  Depth  perception  and  pro- 
jection occur  to  a  considerable  extent  in  smell  and  hearing. 
Odors  are  perceived  not  in  our  nostrils  but  in  the  rose  or 

^  Accommodation  and  convergence  require  time;  these  factors  would  not 
occur  in  instantaneous  exposures. 
^  P.  66. 


160  PERCEPTION  [ch.  vii 

other  outside  object  which  is  the  real  source  of  the  stimulus. 
Sounds  are  localized  outside  the  head,  often  at  a  considerable 
distance. 

The  actual  distance  of  odorous  objects  or  sounds  is  not 
perceived  so  precisely  as  in  sight.  If  we  possess  the  sense 
of  sight  we  usually  project  odors  into  the  objects  that  we  see 
and  measure  the  distance  of  the  source  visually.  The  pro- 
jection of  sounds  is  assisted  by  training.  Certain  sounds 
are  ordinarily  limited  to  a  certain  range  of  intensity.  If 
they  are  softer  or  louder  than  usual,  we  localize  them  far  off 
or  near  by. 

The  cutaneous  senses  (warmth,  cold,  touch)  furnish  a  few 
independent  indications  of  depth  and  projection.  If  we  hold 
our  hands  near  a  hot  stove  we  locate  the  sensation  of  warmth 
outside  the  body  toward  the  stove.  Cold  is  similarly  pro- 
jected when  we  hold  our  hand  near  a  cake  of  ice.  Ordinarily 
our  eyes  are  open  and  there  is  visual  projection  also.  But 
even  with  closed  eyes  some  temperature  projection  takes 
place.  In  touch,  which  is  well  developed  for  surface  percep- 
tion, there  is  only  slight  projection. 

Projection  in  touch  usually  occurs  when  a  rigid  object  con- 
nects the  source  of  stimulation  with  our  touch  receptors. 
When  we  write  with  a  pen  we  feel  the  point  of  the  pen  touch- 
ing the  paper.  When  we  cut  with  scissors  the  touch  sensa- 
tion is  projected  to  the  place  where  the  cutting  occurs.  When 
we  walk  we  feel  the  soles  of  our  shoes  pressing  on  the  ground, 
and  in  using  a  cane  we  feel  the  tip  of  the  cane  where  it  touches 
the  pavement.  Most  singular  of  all,  when  we  dig  with  a 
spade  we  feel  the  impact  of  the  spade  underground  when  it 
strikes  a  stone.' 

All  this  indicates  that  we  have  a  general  tendency  in  pei^ 
ception  to  project  a  sensation  as  far  out  from  the  body  toward 
the  source  as  the  data  warrant.  Even  our  systemic  sensa- 
tions are  projected  from  the  brain  centers  to  their  source  in 
^  In  these  illustrations  the  word  'feel'  means  to  'have  a  perception.* 


CH.  vn]  DEPTH  AND  PROJECTION  161 

the  receptors  within  the  body;  muscle  sensations  of  effort 
are  often  projected  into  objects,  so  that  we  are  apt  to  endow 
inanimate  things  (such  as  the  wind)  with  muscular  power 
and   strength. 

The  space  perception  of  the  blind  is  quite  different  from 
that  of  normal  men.  Blind  persons  perceive  lines  and  sur- 
faces just  as  we  do,  except  that  they  do  not  discriminate 
nearly  so  finely.  But  (1)  they  perceive  all  sides  of  a  solid  at 
once  —  the  back  as  well  as  the  front;  and  (2)  they  do  not 
perceive  objects  in  perspective. 

A  blind  man  perceives  the  shape  of  a  ball  by  putting  his 
hands  around  it;  his  perception  includes  every  part  of  the 
spherical  surface  with  equal  vividness.  To  us,  the  farther 
side  is  hidden  and  does  not  enter  into  the  perception  except 
through  memory  images  or  touch,  so  that  usually  we  perceive 
only  half  the  ball  at  a  time.  And  so  of  objects  generally; 
the  blind  perceive  them  all  around  at  the  same  time;  ordi- 
narily we  do  not.  It  is  not  easy  for  us  to  picture  what  this 
means,  because  our  space  perception  is  so  largely  visual. 
But  if  you  close  your  eyes  and  examine  objects  by  touch,  you 
can  appreciate  the  blind  man's  kind  of  perception  somewhat 
better;  when  you  handle  a  book  or  a  ball  you  get  as  clear  an 
impression  of  the  far  side  as  of  the  side  nearest  you. 

On  the  other  hand,  a  blind  person  has  no  idea  how  anyone 
can  get  perceptions  of  near  and  remote  objects  all  at  once. 
Accommodation,  shading,  convergence,  mean  nothing  to  him. 
To  the  blind,  perception  is  largely  an  exploring  process, 
which  takes  time. 

d.  Perception  of  Objects.  —  When  a  whole  group  of  stimuli 
affect  our  receptors  at  once,  some  of  the  resulting  sensations 
enter  into  the  perception  more  clearly  and  vividly  than  others. 
Usually  there  is  a  *  focus  of  attention  '  comprising  certain 
elements  that  are  especially  clear;  other  parts  of  the  percep- 
tion are  fairly  vivid,  while  others  are  indistinct  or  quite  un- 
noticed.   This  unevenness  in  the  perception  is  partly  due  to 


162  PERCEPTION  [ch.  vii 

differences  in  the  intensity  of  the  stimuli.  A  loud  sound 
usually  occupies  the  focus  of  attention,  while  very  faint 
sounds  which  accompany  it  pass  unnoticed.  A  bright-colored 
pattern  stands  out  prominent,  while  the  dimmer  background 
is  scarcely  observed  at  all. 

There  are  also  differences  of  vividness  in  our  perceptions 
which  do  not  depend  on  the  intensity  of  stimulation.  When 
we  look  at  a  human  face  we  do  not  observe  each  individual 
feature  distinctly.  Usually  the  eyes,  nose,  and  mouth  are 
most  prominent,  the  ears  and  chin  and  the  arrangement  of 
hair  are  noticed  somewhat,  while  the  curves  and  shading  of 
the  cheeks  may  escape  notice  altogether.  These  differences 
are  due  to  attention  and  inattention  —  that  is,  to  the  focus- 
ing of  certain  nerve  impulses  and  inhibition  of  others  at  the 
brain  centers,  where  sensations  are  combined  into  percep- 
tions. The  focusing  process  enables  us  to  perceive  objects 
as  units.  The  human  face  is  seen  as  *  a  face,'  not  as  a  mass  of 
separate  features.  In  looking  about  the  room  you  perceive  a 
number  of  objects  —  chairs,  tables,  books,  etc.  —  each  one  of 
which  is  focused  as  a  distinct  thing,  with  its  individual  fea- 
tures more  or  less  merged  in  the  total  perception. 

The  visual  perception  of  objects  is  strengthened  by  im- 
pressions from  other  senses.  Usually  objects  about  us  stimu- 
late several  senses  at  once.  An  orange  may  affect  the  eyes, 
the  skin,  the  muscles,  the  nostrils,  and  the  taste  receptors. 
We  see,  touch  (or  '  palp  '),  heft,  smell,  and  taste  the  orange, 
all  at  the  same  time.  The  various  sensations  combine  into 
one  single  perception  —  a  perception  of  the  orange  with  its 
many  characteristics.  This  is  object  perception  in  its  most 
developed  form. 

Even  when  some  of  the  characteristic  sensations  are  lack- 
ing we  supply  them  through  memory  elements.  In  looking  at 
an  orange  we  get  an  impression  of  its  taste  and  heaviness. 
An  iron  crowbar  *  looks  heavy  ';  an  aluminium  dish  '  looks 
light.'     All  our  perceptions  of  objects  in  adult  life  are  tinged 


CH.  vii]  OBJECT  PERCEPTION  163 

with  such  memory  elements,  due  to  many  past  experi- 
ences.^ 

The  practical  importance  of  the  non-visual  elements  in  per- 
ception is  greater  than  we  are  apt  to  realize.  We  only 
appreciate  this  when  some  of  these  elements  are  missing.  In 
certain  abnormal  mental  conditions  the  muscle  sensations  are 
cut  off;  the  patient  does  not  feel  the  resistance  of  objects  that 
he  lifts  or  pushes.  Nothing  seems  to  have  weight.  In  such 
cases  the  patient  declares  that  the  things  he  sees  do  not  *  look 
real.'  The  whole  world  about  him  seems  an  illusion,  because 
his  object  perception  is  incomplete:  the  muscular  sensation  of 
resistance  is  absent. 

The  way  in  which  habit  influences  our  perception  of  things 
is  brought  out  if  we  look  at  the  landscape  with  the  head  upside 
down.  The  horizon  seems  much  farther  off ;  the  sky  coloring 
near  the  horizon  is  more  vivid.  In  a  wrong-side  printing  of  a 
photograph  the  right-and-left  reversal  of  buildings  or  animals 
does  not  look  strange  because  we  are  accustomed  to  see  build- 
ings and  animals  turned  either  way.  But  if  printed  letters 
(especially  handwriting)  are  reversed,  they  look  very  strange. 
The  script  in  Fig.  76  ^  is  almost  impossible  to  decipher  unless 
you  look  at  it  in  a  mirror.  This  is  because  words  are  always 
written  in  a  left-to-right  direction  —  never  from  right  to  left. 
The  reversal  of  white  and  black  also  plays  havoc  with  per- 
ception —  it  makes  a  famiUar  face  quite  unrecognizable. 
[Fig.  59.] 

A  special  problem  in  connection  with  object  perception  is 
the  number  of  objects  that  can  be  perceived  distinctly  at  once; 
not  the  total  number  of  details  noticed  at  one  time  (which  may 
be  indefinitely  great),  but  the  number  of  vivid  groups  which 
are  marked  off  as  separate  objects.  This  is  called  the  span  of 
attention.  Experimental  investigations  indicate  that  the  span 
depends  upon  several  factors.     It  is  increased  by  voluntary 

^  In  perceiving  Fig.  52  (p.  144)  certain  visual  memories  are  added. 
«P.  290. 


164 


PERCEPTION 


[cH.  vn 


Pig.  59.  —  Who  is  This? 

Fix  the  white  dot  in  the  center  stead- 
ily for  60  seconds.  Then  look  away 
quickly  to  a  white  surface;  a  negative 
after-sensation  will  appear,  and  there 
should  be  no  difficulty  in  recognizing  the 
portrait    [From  The  Farm  Joumd.] 


attention  and  diminished  by  fatigue.     Under  ordinary  con- 
ditions from  six  to  eight  objects  are  clearly  distinguished 

simultaneously.      The     number 
may  be  increased  with  practice 
to  about  fifteen. 
Objects    and    Space.  —  The 
■■~^^^'  #!^B    space"  relations   of    our    several 
■QM^  U^^B    senses  coincide.     We  feel  (palp) 
^9Bp^  f^^m    our  hand  in  the  same  place  as 
m^'^    I^^m      that  in  which  we  see  it.     The 
^^^m   ^^       taste,  touch,  and  warmth  of  the 
y^^^f  steak  we  are    chewing   are   all 

localized  in  the  mouth.  Our 
field  of  perception  consists  of 
only  one  space,  not  of  separate 
spaces  for  sight,  touch,  and  other 
sensations.  This  is  brought  out 
strikingly  when  the  normal  rela- 
tionship of  the  senses  is  disturbed.  If  you  look  at  your 
hand  through  a  reversing  lens  you  feel  the  fingers  in  a  dif- 
ferent place  from  where  you  see  them.  In  using  a  micro- 
scope you  push  the  slide  in  one  direction  to  move  the  visual 
field  in  the  opposite  direction. 

The  oldest  recorded  contribution  to  experimental  psychol- 
ogy, Aristotle's  experiment,  illustrates  this.  Aristotle  noted 
that  if  the  middle  fingers  are  crossed  and  a  stick  or  marble  is 
placed  between  them  (the  eyes  being  closed),  the  object 
appears  double.  This  is  because  in  ordinary  experience  the 
far  sides  of  these  two  fingers  lie  some  distance  apart  and  are 
never  touched  by  the  same  object. 

Our  integration  of  the  clues  from  various  senses  into  a 
perception  of  one  general  *  space '  is  the  result  of  habit. 
This  can  readily  be  verified.  When  we  become  accustomed 
to  using  the  microscope  the  direction  of  the  slide's  motion  as 
we  see  it,  tallies  with  our  sensation  of  muscular  pull.     One 


CH.  vii]  DEPTH  AND  PROJECTION  1«5 

who  wears  near-sight  glasses  has  no  diflSculty  in  touching 
objects  in  the  exact  place  where  he  sees  them,  though  when 
he  first  wore  glasses  everything  appeared  slightly  displaced. 
That  we  can  learn  to  combine  properly  our  various  space 
perceptions  even  under  most  exceptional  conditions,  is  proved 
by  Stratton's  experiment. 

Stratton  wore  a  large  reversing  lens  continuously  for  seven 
days,  removing  the  apparatus  only  at  night,  when  his  eyes 
were  kept  bandaged.  Seen  through  this  lens  the  whole  field 
of  vision  was  turned  completely  around,  like  the  picture  on 
a  camera  plate.  With  respect  to  touch  and  muscle  sense 
his  left  hand  was  seen  at  the  right  side,  his  feet  were  above  his 
head,  the  lintel  of  a  door  was  where  the  threshold  ought  to  be. 
At  the  end  of  the  week  he  found  that  the  space  relations  were 
almost  completely  reintegrated  to  meet  the  new  conditions. 
He  reached  for  things  where  he  saw  them  and  manipulated 
implements  properly.  He  felt  his  hands,  feet,  and  body  in 
the  same  place  and  in  the  same  relations  as  their  visual  pic- 
tures. Only  the  position  of  the  head,  which  had  not  been 
seen  during  the  experiment,  tended  to  remain  in  its  old 
relations  —  its  localization  was  confused  and  vacillating. 

e.  Perception  of  Time  and  Events.  —  Most  stimuli  persist 
for  some  time,  and  the  sensations  which  they  produce  persist 
too.  When  you  are  looking  at  an  object  and  it  moves  or  disap- 
pears or  changes,  the  nerve  impulses  in  the  brain  centers  do 
not  immediately  cease  or  alter  all  at  once.  There  is  usually  a 
certain  period  during  which  the  old  perception  is  fading  away 
and  the  new  perception  is  beginning.  In  other  words,  suc- 
cessive perceptions  dovetail  together;  we  perceive  at  one  and 
the  same  instant  both  the  incoming  and  the  outgoing  events. 
The  *  now '  of  perception  is  not  the  same  as  the  physicist's 
idea  of  *  the  present.'  It  is  not  a  thin  knife-edge  separating 
the  past  from  the  future,  but  a  fair-sized  period  of  time. 
The  perceptual  present,  as  it  is  called,'  may  cover  as  much  as 
1  It  is  also  called  the  'specious  preseot.' 


166  PERCEPTION  [ch.  vn 

six  seconds.  All  impressions  within  this  period  of  time  may  be 
present  to  you  at  once.  This  is  what  makes  it  possible  for  you 
to  perceive  changes  and  events  as  well  as  stationary  objects. 

When  you  see  a  man  running  you  get  a  series  of  visual  sen- 
sations of  his  various  positions.  These  successive  sensations 
are  all  embraced  in  one  perceptual  moment,  and  they  com- 
bine into  a  perception  of  running.  Examine  the  instanta- 
neous photographs  of  a  man  walking.  No  one  of  them  is 
specially  characteristic,  and  some  look  absurd.  Your  per- 
ception of  walking  is  an  integration  of  the  whole  series;  the 
absurd  positions  are  not  noticed.  The  pictures  of  a  man 
jumping  or  of  a  horse  galloping  show  this  even  more  strik- 
ingly. You  have  a  very  definite  visual  perception  of  the 
act  as  an  event,  though  every  one  of  the  instantaneous  poses 
looks  unreal  and  ridiculous.  The  same  is  true  of  other  com- 
mon actions.  Many  activities  of  inanimate  nature  are  per- 
ceived as  events  rather  than  as  a  succession  of  situations; 
the  lashing  of  surf  on  the  beach,  the  fall  of  a  leaf,  the  flapping 
of  a  sail,  and  the  waving  of  a  tree  in  the  wind  are  perceived  as 
*  happenings.' 

In  the  sense  of  hearing,  successive  sounds  tend  to  combine 
into  definite  groups,  particularly  in  music.  A  tune  is  com- 
posed of  a  series  of  groups,  each  consisting  usually  of  3  or  4 
successive  tones.  One  tone  in  each  group  is  accentuated  in 
some  way :  the  accented  tone  may  be  louder  than  the  others, 
or  it  may  be  slightly  prolonged,  or  the  effect  may  be  due  to  an 
accompanying  pattern  (dum-da-da-dum-da-da)  in  the  bass. 
This  grouping  of  sounds  by  accentuation  is  called  rhythm. 
Rhythm  occurs  in  poetry  as  well  as  in  music.  Even  when 
there  is  nothing  in  the  stimuli  to  cause  it,  we  tend  to  perceive 
sound  successions  in  a  rhythmic  way.  We  weave  a  rhythm 
pattern  into  the  ticking  of  a  clock  and  into  the  clicks  of  the 
wheels  on  a  moving  train.  We  do  not  have  to  make  an  effort 
to  get  the  effect;  it  is  diflBcult  not  to  get  it. 

A  musical  time  is  perceived  as  an  event,  just  as  visual  acts 


CH.  vuj  TIME  PERCEPTION  167 

are  perceived  as  events.  The  rhythmic  pattern  is  the  basis 
of  the  grouping,  and  the  tone  differences  complete  the  effect. 
The  development  of  tune-perception  may  be  observed  in  the 
army  bugle  calls.  When  you  first  hear  them,  they  appear  as 
mere  tone-successions;  one  call  seems  scarcely  different  from 
another-  After  a  time  the  tattoo,  reveille,  taps,  and  other 
calls  acquire  individuality,  like  the  familiar  visual  objects 
of  every-day  life. 

Illusions.  —  Our  perception  of  the  quahties  and  relations  of 
objects  is  remarkably  exact.  It  tallies  very  closely  with  the 
qualities  and  relations  of  the  objects  themselves  —  far  more 
closely,  indeed,  than  would  be  expected  from  a  study  of  the 
senses.  The  fact  that  the  visual  receptors  are  located  in  one 
place,  the  auditory  receptors  in  another,  the  taste  bulbs  in  a 
third,  might  lead  one  to  suppose,  if  he  had  no  senses  of  his 
own,  that  a  human  being  would  see  things  in  one  place,  hear 
them  in  another,  and  so  on.  The  fact  that  sepxarate  nerve 
paths  lead  from  each  rod  and  cone  in  the  eye  and  from  each 
touch  corpuscle  in  the  skin  to  the  brain,  and  that  the  various 
sense  centers  are  some  distance  apart  in  the  cortex,  would 
confirm  this  supposition.  Yet  the  opposite  is  true.  We  tend 
to  group  our  sensations  into  relations  just  like  those  of  the 
objects  which  arouse  them,  and  we  project  all  our  various 
sensations  —  visual,  auditory,  and  the  rest  —  from  any  given 
object  into  one  and  the  same  set  of  space  relations.  We 
perceive  it  as  one  objecL 

Considering  the  intricacy  of  the  perception  process  and  the 
number  of  factors  involved,  it  is  certainly  not  remarkable  that 
our  perceptions  are  sometimes  inexact  —  that  they  do  not 
always  show  us  the  true  relations  of  objects  in  the  environ- 
ment. Perception  depends  largely  on  habit,  and  when  our 
present  sensations  conflict  with  some  firmly  established  habit 
of  recei\nng  experiences,  an  '  untrue '  perception  arises. 
A  perception  which  does  not  correspond  to  the  actual  situar 
tion  in  the  environment  is  called  an  illusion. 


168  PERCEPTION  [ch.  vii 

The  illusions  that  occur  in  connection  with  space  per- 
ception are  especially  interesting  to  psychologists.  Some  of 
these  have  already  been  described.  There  are  many  others 
which  we  notice  constantly  in  daily  life.  If  we  look  at  a 
motion  picture  taken  from  the  front  of  a  moving  train,  it  is 
diflScult  not  to  get  the  impression  that  we  ourselves  are 
rushing  forward.  This  is  because  ordinarily  we  get  the 
relative  motion  of  objects  only  when  we  move.  When  we  look 
down  from  a  tall  building  the  people  below  seem  very  small, 
because  the  superposition  of  nearer  objects  to  which  we  are 
accustomed  is  lacking,  and  this  counterbalances  the  factor  of 
their  known  size.  The  objects  seen  in  the  stereoscope  appear 
large  and  distant,  because  the  convergence  sensations  are  like 
those  that  we  ordinarily  get  in  looking  at  distant  objects. 

The  bits  of  memory  and  imagination  that  enter  into  our 
perceptions  are  often  powerful  factors  in  producing  illusions. 
How  many  readers  on  first  looking  over  chapter  v  of  this 
book,  read  systematic  instead  of  systemic^  sensations?  You 
imagined  you  saw  the  more  familiar  word.  Mistakes  in 
printing  are  due  to  this  principle.  The  printer's  perception 
of  words  in  the  copy  is  influenced  by  his  memory  pictures; 
or  accidental  errors  in  composition  are  overlooked  by  the 
proof-reader.  Such  mistakes  occur  in  the  most  carefully 
printed  books.  Fig.  52  is  another  variety  of  the  same  illusion. 
It  is  almost  impossible  not  to  see  the  outlines  of  the  letter 
COME,  even  where  they  are  actually  missing. 

Another  class  of  illusions  occur  in  pictures  that  can  be 
perceived  in  two  different  ways.  This  double  interpretation 
often  occurs  in  geometrical  patterns.  Take  the  common  oil- 
cloth patterns  in  two  colors.  At  times  you  see  a  figure  of  one 
color  on  a  background  of  the  other.  Then  it  changes  about; 
the  second  color  becomes  the  pattern  and  the  first  is  the  back- 
ground. Fig.  60  is  a  whimsical  case  of  double  interpretation. 
Does  the  picture  represent  a  rabbit  or  a  duck.? 

Often  this-  sort  of  illusion  results  in.  reversible  perspective. 


CH.  vn] 


ILLUSIONS 


169 


In  Fig.  61  you  can  perceive  the  black  faces  either  as  under 
surfaces  or  as  upper  surfaces  of  the  cubes;  in  one  case  you  see 
seven  cubes,  in  the  other  six.     The  cube  in  Fig.  62  app>ears 


Pig.  60.  —  Double  Inter- 
pretation 

Is  this  a  rabbit  or  a  duck?     [From 
Jastrow,  after  Harper's.] 


readily  in  two  positions  — 
either  the  lower  or  the  upper 
central  point  looks  nearer. 
With  practice  one  can  make  the  cube  shift  back  and  forth 


FiQ.  61.  —  The  Illusory 
Cubes 

How  many  cubes  do  you  see  —  6  or  7? 
[From  Jastrow.] 


Fia.  62.  —  The 

Reversible 

Cube 

Is  the  lower  mid- 
point nearer  you,  or 
the  upper? 


Fig.  63.  —  The  Reversible  Staircase 

At  first  this  looks  like  an  ordinary  flight  of  stairs. 
By  focusing  on  the  upper  jagged  line  (and  pulling  it 
toward  you)  the  staircase  turns  over  and  looks  like ' 
cellar  stairs  seen  from  underneath. 


at  will.     The  staircase  [Fig.  63]  is  not  so  easy  to  shift.     We 
are  more  accustomed  to  see  the  upper  surface  of  stairs  than 


170 


PERCEPTION 


[cH.  vn 


their  under  side.  If  we  lived  in  cellars  the  reversal  would 
be  easier.  By  recalling  how  cellar  stairs  look  from  under- 
neath we  are  greatly  aided  in  reversing  the  perspective;  but 
most  observers  report  that  the  upper-side  eJBFect  lasts  much 
longer  than  the  other,  even  after  practice. 

Certain  illusions  are  due  to  eye  Tnovements  that  are  not 
properly  taken  into  account  JjQ  perception.      The  muscle 


<> 


Muller-Lyeb  Illusion 


The  distance  between  apex  of  left  and  apex  of  central  figure  appears  longer 
than  that  between  central  and  right.    The  two  distances  are  equal. 

sensations  report  to  us  the  actual  movements  of  the  eyes  (or 
their  tendencies  to  movement),  which  may  be  greater  or  less 
than  the  distances  they  are  supposed  to  cover;  and  our  per- 
ceptions overestimate  or  underestimate  the  distances  accord- 


'-^^^:$:$^\IIM^^^>:>^ 

jn^^^^^^^ 

:::<;^^\\^^:^ 

Fig.  65.  —  Hebino  Illusion 

The  horizontal  lines  appear  to  bend  apart  in  the  middle.    They  are  paralleL 

ingly.  In  the  Miiller-Lyer  illusion  [Fig.  64]  the  distance  from 
the  left  point  to  the  middle  point  looks  considerably  longer 
than  that  from  the  middle  to  the  right;  the  two  distances  are 
really  equal.     In  the  Hering  illusion  [Fig.  65]  the  two  hori- 


CH.  vn] 


ILLUSIONS 


171 


zontal  lines  look '  bow-legged,'  though  they  are  really  parallel. 
The  Zollner  and  Poggendorff  patterns  are  illusions  of  the  same 
sort.    [Figs.  66  and  67.] 

When  we  look  at  the  Miiller-Lyer  figure,  the  eye  does  not 
travel  from  apex  to  apex  as  we  suppose,  but  from  some  point 


Fig.  66.  —  Zollner  Illusion      ^ 

The  horizontal  lines  appear  to  be  slightly  tilted  —  the  upper  one  slanting  down  to  the  right, 
next  slanting  up,  etc.    They  are  all  parallel. 

inside  the  first  angle  to  a  corresponding  point  inside  the 
second,  and  then  to  a  point  inside  the  third.  This  makes  the 
left  distance  appear  longer,  because  the  eye  travels  farther, 
with  greater  muscle  sensations.  (The  eyes  may  not  make  the 
actual  movements,  but  there  is  always  a  tendency  to  the  move- 
ment and  this  is  accompanied  by  muscle  sensations,  which 
determine  our  appreciation  of  the  distance.)  In  the  Zollner 
figure  the  cross-lines  divert  the  eye  slightly  from  the  hori- 
zontal path,  so  that  the  horizontal  Unes  seem  to  tilt  upward 
or  downward,  as  the  case  may  be.  The  other  illusions  depend 
on  similar  muscle-sense  factors. 

Relation  of  the  Brain  to  Perception.  —  Perception  is  a 
higher  mental  process  than  sensation.  Sensation  is  merely 
the  reception  in  the  brain  centers  of  nerve  impulses  from 
the  sense  organs.  Perception  works  this  sensation  material 
into  shape.     It  includes  composition  of  sensations,  focusing 


17£ 


PERCEPTION 


[cH.  vn 


(attention  to  parts),  revival  of  memory  elements,  and  dis- 
crimination. 

The  elements  which  make  up  our  perceptual  experiences 
are  chiefly  sensations  from  the  external  senses,  reinforced  by 
muscle  sensations  and  memory  ele- 
ments. This  material  is  put  together 
and  modified  by  central  nervous  ac- 
tivities, so  that  the  perception  cor- 
responds more  nearly  to  the  general 
situation  in  the  outer  world  than  the 
separate  stimuli  do. 

The  way  in  which  the  elementary 
sensations  combine  into  perceptions 
depends  largely  upon  the  inherited 
structure  of  our  central  nervous  sys- 
tem. Sensory  neurons  which  he  near 
together  in  the  brain  and  readily 
connect  with  a  single  higher  path- 
way, tend  to  furnish  group  impres- 
sions. For  instance,  the  optic  nerve 
fibers  connect  together  in  the  visual 
centers,  so  that  all  visual  sensations 
which  occur  simultaneously  tend  to 
unite  into  a  single  experience.  The 
same  is  true  of  auditory  impressions  and  other  types.  The 
sight  of  a  red  disk,  or  the  sound  of  a  complex  chord,  belongs 
to  the  simplest  type  of  perception;  this  simple  grouping  of 
sensations  probably  takes  place  in  the  primary  centers.  Per- 
ceptions which  bring  various  senses  together,  such  as  the  im- 
pression of  a  cold,  heavy,  glittering  cake  of  ice,  involve  the 
use  of  association  fibers  which  gather  the  sensory  material 
from  several  primary  centers  into  a  higher  center.  This 
results  in  perception  of  objects. 

The  natural  grouping  of  impressions  due  to  inherited 
nervous  pathways  is  supplemented  by  the  retention  of  past 


Fig.  67.  —  Poggendorff 
Illusion 

The  upper  cross-line  appears 
to  be  the  continuation  of  the  line 
starting  at  B.  It  is  really  the  con- 
tinuation of  A. 


CH.  vn]       SIGNIFICANCE  OF  THE  BRAIN  173 

efiPects  and  previous  connections  in  the  brain.  Our  percep- 
tion of  familiar  objects  and  common  events  involves  some- 
thing more  than  present  sensations;  it  includes  the  memory 
of  similar  past  experiences.  Our  perception  of  a  friend's 
face  when  we  see  it  in  full  front,  includes  a  vague  impression 
of  his  profile  and  the  back  of  his  head,  due  to  memory.  The 
more  frequently  we  observe  the  same  object  or  occurrence, 
with  sUght  variations,  the  fuller  and  richer  does  our  percep- 
tion of  it  become.  The  absence  of  these  memory  elements 
interferes  with  perception,  as  in  the  case  of  reversed  hand- 
writing. 

The  highest  development  of  perception,  then,  depends  (1) 
upon  the  presence  of  a  mass  of  inherited  association  fibers 
connecting  the  various  sensory  centers  in  the  brain,  and  (2) 
upon  the  formation  of  definite  nerve  connections  and  paths 
by  means  of  these  fibers,  and  the  retention  of  such  effects. 

Training  of  Perception.  —  The  development  of  perception 
proceeds  in  two  opposite  directions  —  composition  and  dis- 
crimination. (1)  Perception  enables  us  to  grasp  objects  and 
events  as  a  whole.  Common  experiences  are  soon  consoli- 
dated in  this  way.  We  see  a  house  as  a  single  object.  It  is 
something  to  live  in.  The  front  path  is  the  means  of  reach- 
ing the  house;  the  steps  are  for  climbing,  the  door  is  for  enter- 
ing the  house.  Each  of  these  perceptions  is  associated  with 
some  idea  of  possible  action  on  our  part.  These  associated 
ideas  make  up  the  meaning  of  the  perception.  The  impor- 
tance of  '  meaning  '  is  brought  out  strikingly  in  our  experi- 
ences with  unfamiliar  objects.  The  countryman  tries  to  pull 
or  twist  the  door-bell  button  instead  of  pushing  it.  He  does 
not  perceive  its  meaning. 

(2)  The  second  direction  in  which  perception  develops  is  in 
giving  emphasis  to  certain  features  at  the  expense  of  others. 
We  pick  out  this  or  that  detail  which  relates  to  our  own  gen- 
eral experience.  The  artist  perceives  at  a  glance  some  tech- 
nical blunder  in  a  painting  which  most  of  us  never  notice. 


174  PERCEPTION  [ch.  vii 

The  ornithologist  sees  the  nest  in  a  high  fork  of  a  tree.  The 
expert  proof-reader's  eye  sometimes  catches  an  error  on  the 
printed  page  before  he  has  read  a  single  word. 

As  our  field  of  experience  enlarges,  our  perceptions  develop 
in  both  these  directions  even  without  special  training.  We 
learn  naturally  to  see  the  things  which  bear  on  our  own 
interests,  and  to  pick  out  details  which  have  special  signifi- 
cance for  us.  The  guide  in  the  wilderness  sees  trail  signs 
which  the  ordinary  traveler  cannot  detect  even  when  they 
are  pointed  out  to  him. 

The  need  for  training  is  rather  in  lines  outside  our  own 
interests.  The  child  at  the  outset  needs  to  be  trained  espe- 
cially in  the  phases  of  perception  which  do  not  develop  readily 
under  ordinary  conditions.  Sight  is  the  dominant  sense; 
it  needs  less  cultivation  than  any  of  the  other  senses.  If  you 
compare  a  child's  performances  on  the  form-board  [Fig.  68] 
with  that  of  a  grown  person,  you  will  find  that  the  child  takes 
much  longer  to  fit  the  pieces  into  the  right  holes.  Blindfold 
the  adult  and  you  will  find  that  he  makes  the  very  same  errors 
that  the  child  makes  with  eyes  open,  and  takes  as  long  a  time. 
The  touch  perception  of  the  adult  remains  immature,  while 
his  visual  perception  has  developed  far  beyond  the  child's. 
This  means  that  the  average  man's  touch  perception  has  not 
been  properly  trained. 

An  important  task  in  primary  education  should  be  to  train 
perception  in  touch,  muscle  sense,  hearing,  and  other  senses. 
The  child  should  be  taught  to  discriminate  and  to  build  up 
object-perceptions  in  these  fields.  The  special  problem  is  to 
accomplish  this  without  boring  the  child  —  to  train  him 
through  play  activities  which  keep  his  interest  aroused.  This 
is  the  underlying  principle  of  all  kindergarten  methods.  The 
Montessori  system  of  primary  education  has  been  especially 
successful  here. 

Systematic  training  of  perception  would  benefit  almost 
every  one  in  later  life.     Some  of  us  are  naturally  slovenly 


176  PERCEPTION  [ch.  vn 

observers.  If  we  realize  this  fault,  the  very  realization  is  an 
incentive  to  train  ourselves  in  careful  observation.  Perhaps 
we  do  not  notice  the  color  of  people's  eyes;  this  is  not  impor- 
tant, but  it  is  often  useful  for  identification.  Make  it  a  point 
to  note  the  color  of  every  one's  eyes  for  a  while;  once  the 
habit  is  formed  it  will  be  kept  up  automatically.  And  so  of 
any  other  detail.  It  is  impossible  to  observe  every  detail  in 
the  things  about  us  —  and  too  great  minuteness  of  observa- 
tion is  a  waste  of  attention.  But  most  of  us  err  in  the  other 
direction. 

A  noted  conjuror  tells  how  he  and  his  brother  made  a 
practice  of  running  past  a  show  window,  and  then  trying  to 
describe  as  many  as  possible  of  the  things  displayed.  Train- 
ing of  this  sort  would  be  useful  to  most  persons.  It  fosters 
habits  of  more  precise  observation  and  better  retention. 

Summary.  —  In  this  chapter  we  begin  the  study  of  diflFerent 
kinds  of  experiences.  Perceptions  are  composed  of  a  great 
number  of  external  sensations,  put  together  so  as  to  show  us 
objects  and  events  in  the  world  around  us.  The  most  impor- 
tant process  in  perception  is  to  get  the  spatial  relations  of 
things  to  one  another  (surface)  and  to  our  body  (depth  or 
projection).  Perceptions  are  usually  *  true  to  life,'  but  we 
sometimes  misinterpret  the  evidence,  and  this  gives  rise  to 
certain  striking  illusions. 

Phactical  Exercises: 

33.  Examine  how  far  your  depth  perception  depends  upon  each  of  the 
eight  factors  mentioned  in  the  text. 

34.  Place  several  upright  rods  at  various  distances  from  your  eyes.  Close 
each  eye  separately  and  observe  the  different  effects;  compare  these 
with  the  effect  when  both  eyes  are  open. 

85.  Study  a  pair  of  stereoscopic  pictures  with  and  without  the  instrument. 
Report  the  stereoscopic  experience  and  its  relation  to  the  two  separate 
pictiu:«s. 

86.  Observe  the  motions  of  your  hand  when  seen  only  in  a  mirror,  e.g., 
in  shaving,  hair-brushing,  or  writing;  report  the  nature  of  your  diffi- 
culties, and  whether  you  can  'feel'  your  hand  where  you  see  it. 

87.  Test  the  'staircase  illusion*;  note  the  eye  movement,  use  of  volition, 
time,  etc.,  in  changing  from  one  perspective  to  the  other. 


CH.  vn]  SUMMARY  177 

88.  Glance  for  one  second  at  a  shop  window  as  you  walk  by.  Write  down 
what  objects  you  perceived.  Repeat  for  several  shops  and  note  the 
number  of  perceptions  obtained  for  each. 

References: 
On  space  perception  and  illusions:  W.  James,  Principles  of  Psychology,  chs. 

19,  20;  E.  Mach,  Analysis  of  the  Sensations. 
On  Stratton's  experiment:  G.  M.  Stratton,  in  Psychological  Review,  1897, 

4,341-360.463-481. 
On  illusions:  E.  C.  Sanford,  Course  in  Experimental  Psychology,  ch.  7; 
J.  E.  W.  Wallin,  Optical  Illusions  of  Reversible  Perspective. 


CHAPTER  Vin 
MEMORY  AND  IMAGINATION 

Imagery.  —  Human  experiences  consist  largely  of  percepn 
tions  of  the  things  around  us  and  reproductions  of  these  per- 
ceptions.    Our  perceptions  may  be  reproduced  in  the  form  of 

ideas,  when  the  external  objects  are  absent.  There  are  taro, 
stages  in  the  growth  of  ideas:  imagery  and  thought.^  Images 
appear  earlier  in  evolution  than  thoughts  and  bear  a  closer 
resemblance  to  the  original  perceptions.  Mankind  is  capable 
of  several  kinds  of  imagery: 

Memory  images 
Imagination  images 
Anticipation  images 
Composite  images 
General  images 

Memory  and  imagination  occur  the  most  frequently  and 
are'  very  important  in  human  life,  especially  among  civilized 
peoples.  A  memory  reproduces  more  or  less  exactly  some 
former  experience,  while  an  imagination  is  unlike  any  previ- 
ous perception.  You  remember  what  actually  happened  to 
you;  you  imagine  things  that  never  happened  to  you  before. 
But  imagination  images  are  not  composed  of  new  material: 
every  part  of  the  experience  is  the  reproduction  of  some 
earher  sensation;  the  originality  consists  merely  in  working 
these  bits  together  in  a  new  way. 

Some  of  our  memories  are  also  imaginations.  We  may 
remember  something  we  have  already  imagined,  instead  of 
what  we  have  already  perceived.  As  children  my  chums  and 
I  imagined  a  weird,  fantastic  vehicle  called  a  Gobblestraw,  in 
which  we  fancied  ourselves  riding.  To-day  I  can  remwnber 
^  Thought  is  a  higher  type  and  will  be  treated  later  (ch.  ziii). 


CH.  vni]  IMAGERY  179 

this  imaginary  coach  as  well  as  any  real  carriage;  the  experi- 
ence is  a  memory  image  of  an  imagination  image,  because 
the  vehicle  never  existed. 

An  jmage  is  not  necessarily  a  visual  experience  —  it  may 
belongto  any  of  the  senses  or  to  several.  We  remember 
tunes  and  odors.  We  can  imagine  hearing  a  friend  say  things 
which  he  never  actually  said.  In  popular  language  the  word 
image  isjisually  applied  to  something  visualized;  in  psychol- 
ogy it  is  used  in  a  broader  way,  to  include  reproduced  sensory 
experiences^of-iaigyj/  eoi4. 

The  chief  distinction  between  images  and  perceptions, 
when  we  compare  them  as  actual  experiences,  is  a  differgiice 
in  intensity.  Memories  are  like  the  original  perceptions  so 
far  as  qualities  are  concerned  —  but  they  are  ordinarily 
much  fainter.  Compare  your  memory  of  a  thunder-clap 
with  the  real  thing;  or  compare  your  memory  of  how  your 
room  looks  with  the  actual  perception.  The  feeble  intensity 
of  the  image  in  each  case  is  striking.  We  usually  know  at 
once  and  without  question,  from  the  very  nature  of  the 
experience,  whether  it  is  a  perception  of  something  outside 
our  body,  or  merely  a  mental  reproduction. 

Images  of  systemic  and  motor  sensations  may  occur  as  well 
as  images  of  external  things.  At  times  we  have  experiences 
of  this  sort,  but  they  do  not  count  for  much.  This  is  because 
we  can  usually  arouse  systemic  and  motor  sensations,  so  that 
we  do  not  need  to  imagine  or  remember  them.  When  you 
imagine  yourself  getting  angry  you  assume  a  certain  bodily 
attitude  which  arouses  actual  sensations  of  anger.  If  you 
remember  making  a  certain  movement  your  muscles  tend  to 
contract  slightly  and  you  get  muscle  sensations  instead  of 
muscular  memories.  So  it  comes  about  that  systemic  and 
muscular  memories  and  images  do  not  often  develop  into 
important  experiences.  External  stimuli  cannot  be  so  easily 
controlled  as  our  own  bodily  processes  and  muscular  move- 
ments; we  cannot  see  or  hear  things  unless  the  objects  are 


180  MEMORY  AND  IMAGINATION      [ch.  vra 

there  to  stimulate  our  senses.  This  lack  is  met  by  the  devel- 
opment of  imagery,  which  supplements  our  perceptions. 

Nature  of  Memory.  —  If  some  one  asks  you  what  you  had 
for  breakfast  this  morning,  you  at  once  get  a  mental  picture 
of  the  dining-room  with  the  table  spread  for  the  meal.  At 
each  seat  is  a  napkin  in  front,  a  fork  and  small  plate  to  the 
left,  a  knife,  spoons,  and  a  tumbler  to  the  right.  You  picture 
other  definite  details  of  the  meal,  including  the  taste  of  the 
prunes,  and  the  uncomfortable  warmth  of  the  coffee-pot 
handle.  All  these  items  are  part  of  your  present  experience; 
but  they  are  not  perceptions.  No  such  stimuli  strike  your 
eyes  or  mouth  at  the  present  moment. 

What  causes  the  memory  experience?  It  is  started  by  the 
question  that  was  asked  you.  You  heard  the  word  breakfast. 
The  nerve  impulse  which  brought  up  this  word  in  your  center 
for  hearing  finds  a  path  open  into  another  center  in  your 
brain,  in  which  there  are  deep  traces  left  by  your  breakfast 
experience  this  morning.  Because  of  these  traces  the  nerve 
impulse,  when  it  passes  into  that  center,  takes  a  form  similar 
to  that  during  the  previous  experience,  when  you  were  actu- 
ally breakfasting;  so  that  you  have  memory  images  like  the 
,  perceptions  which  occurred  at  breakfast  time. 

Every  memory,  or  at  least  every  actual  recollection,  is  due 
(1)  to  traces  left  in  the  brain  substance  by  past  experiences, 
and  (2)  to  some  new  nerve  impulse  which  enters  the  region 
where  these  traces  have  been  left,  and  causes  activity  of  the 
same  sort  as  before.  The  two  essential  iactors-in jmemory 
(and  in  imagination  as  well)  are  retention  and  revival;^ 

The  popular  notion  of  meniOTy^is  that  the  image  itself  is 
stored  away  in  the  mind  or  brain.  This  is  not  true,  though 
one  can  readily  see  how  the  notion  arose;  it  is  merely  attribut- 
ing to  memory  what  actually  occurs  in  perception.  Objects 
in  the  world  about  you  continue  to  exist  even  when  you  do 
not  perceive  them.  You  see  the  breakfast  table,  you  go  out 
of  the  room,  and  when  you  return  you  see  the  table  again; 


CH.  viii]  NATURE  OF  MEMORY  181 

it  is  there  all  the  time.  Men  naturally  assumed  that  mental 
images  continue  to  exist  when  we  are  not  observing  them, 
just  like  objects. 

The  truth  of  the  matter  is  that  the  memory  image  Hoes  not 
TCrsist,  j)ut  only  the  traces  in  the  nerve  substance.  What 
remains  within  the  brain  is  not  a  'picture  of  the  object  or  event, 
but  a  record.  This  lasting  record  does  not  resemble  the  object, 
nor  is  it  like  the  original  sensation.  It  is  analogous  to  a  phono- 
graph record,  where  the  traces  are  not  at  all  like  the  words  or 
music  which  they  represent,  but  are  capable  of  bringing  about 
a  repetition  of  the  words  or  music  under  proper  treatment. 
Like  all  analogies  this  is  not  quite  exact.  The  memory  image 
is  not  produced  by  a  needle  or  anything  like  a  needle.  The 
truth  is  that  the  present  nerve  impulse  is  shaped  by  the  traces 
into  the  same  form  as  the  previous  nerve  impulse. 

Besides  (1)  retention  and  (2)  revival,  there  are  two  other 
factors  in  memory:  (3)  location  in  time  and  space,  and  (4) 
familiarity.  These  belong  to  memory  alone,  and  distinguish  it 
from  imagination  and  other  sorts  of  imagery. 

Location  means  that  a  memory  is  always  given  a  more  or 
less  definite  setting  in  time  and  space.  In  the  case  of  the 
breakfast  memory,  your  image  is  projected  out  from  this  room 
into  the  dining-room  of  a  certain  building  in  this  town  (spatial 
setting)  and  is  projected  back  to  this  morning  (temporal 
setting).  The  recollection  of  my  first  trousers  is  definitely  lo- 
cated in  a  certain  New  Jersey  village  and  in  May  or  June  of  a 
certain  year. 

The  projection  of  memories  is  neither  so  definite  nor  so 
instantaneous  as  the  projection  of  perceptions.  Often  you 
recall  that  you  '  have  seen  this  person  before  *  without  any 
clear  idea  of  where  or  when  it  happened.  In  projecting  a 
memory  image  we  fill  in  the  intervening  space  and  time 
between  ourselves  '  here  —  now  '  and  the  original  occurrence 
*  there  —  then '  by  means  of  clues,  just  as  we  use  clues  in 
depth  perception;  but  memory  projection  is  not  so  vivid  nor  so 


189  MEMORY  AND  IMAGINATION      [cm.  vm 

convincing  as  perceptual  projection.  When  you  look  out  of 
the  window,  the  tall  tree  you  see  is  unmistakably  just  across 
the  street.  When  you  look  back  at  a  certain  convereation  with 
your  best  friend  the  time  and  space  projection  may  be  uncer- 
tain —  it  may  have  two  or  more  possible  locations. 

The  space  location  of  memories  is  determined  by  several 
clues,  such  as  prior  location,  verbal  associations,  and  accompany- 
ing details.  When  you  recall  some  incident  of  childhood  you 
locate  the  experience  in  your  home  town,  because  you  have 
already  built  up  a  set  of  memories  in  which  your  childhood 
experiences  are  located  in  this  place.  Central  Park  is  well 
known  to  the  New  Yorker.  He  has  assimilated  it  to  a  lot  of 
memory  images.  So  when  he  recalls  some  event  in  a  Central 
Park  setting,  the  prior  localization  enables  him  at  once  to 
project  the  event  into  that  place. 

The  memory  itself  may  include  some  name  which  identifies 
the  localization.  The  word  'home'  and  the  name  '  Woolworth 
Building '  are  clues  that  enable  us  at  once  to  project  certain 
occmrences  into  definite  locations.  These  are  verbal  associa- 
tions. 

If  we  recall  a  town  with  picturesquely  colored  houses,  the 
coloring  may  at  once  locate  the  scene  in  Italy.  If  the  houses 
have  curved  roofs  we  project  the  memory  to  Japan  or  China. 
The  memory  of  salt,  sea-weedy  odors  will  place  the  scene  on 
the  sea  coast.  Any  such  accompanying  detail  may  serve  to 
locate  the  memory  image  in  space. 

The  time  location  of  memory  is  also  determined  by  a  num- 
ber of  clues.  Among  civilized  races  verbal  associations  are 
usually  the  most  important  indication.  The  calendar,  with 
its  system  of  days,  months,  and  years,  assists  us  to  project  a 
memory  back  to  the  proper  time.  If  I  recall  the  conference  of 
psychologists  when  America  entered  the  World  War,  I  can 
easily  fix  the  time  by  the  calendar  date,  April  6,  1917. 

Often  we  have  a  succession  of  memories  connected  together. 
They  occur  in  a  certain  order  and  the  series  appears  in  a  tim^ 


CH.  vin]  NATURE  OF  MEMORY  183 

perspective  which  is  not  unlike  the  space  perspective  of  percepn 
tions.  We  recall  the  progress  of  a  Presidential  campaign  in 
this  way  —  the  discussion  of  possible  candidates,  the  nomina- 
tions, the  principal  addresses,  and  finally  the  election.  The 
natural  sequence  of  these  events  enables  us  to  arrange  the 
memories  in  perspective. 

Even  where  there  is  no  chain  of  memories,  the  change  of 
conditions  in  the  worid  is  frequently  a  decisive  clue.  Your 
memory  of  a  conversation  with  some  one  who  has  died,  is 
projected  back  to  a  time  earlier  than  the  date  of  his  death. 
When  you  recall  some  childish  question  of  an  old  friend,  the 
memory  of  his  piping  voice  or  his  knickerbockers  fixes  the 
incident  in  boyhood  days.  My  memory  of  a  visit  to  the 
Windsor  Hotel  in  New  York  jumps  back  at  once  to  a  time 
before  that  hotel  burned  down,  though  it  seems  much  more 
recent. 

A  sense  of  familiarity  is  the  mark  that  distinguishes  memory 
most  clearly  from  other  kinds  of  imagery.  There  is  a  '  sense 
of  realness  '  about  a  memory  which  is  lacking  in  a  mere  thought 
or  imagination.  In  picturing  the  breakfast  incident  there  is  a 
feeling  that  it  reaUy  happened  —  that  the  situation  actually 
existed  in  the  physical  world  and  is  not  imaginary.  This 
feeHng  can  be  readily  observed  in  any  memory  —  a  lecture  you 
heard  last  week,  a  street  scene  some  time  ago,  an  incident  of 
your  childhood. 

The  feeling  of  familiarity  may  be  explained  in  terms  of 
nerve  activity.  It  is  due  to  the  traces  retained  in  the  brain 
substance.  When  a  nerve  impulse  enters  the  brain  centers  it 
encounters  less  resistance  if  there  are  definite  traces  in  these 
centers  than  if  it  has  to  make  a  new  path.  This  ease  of 
passage  through  the  synapses  is  what  gives  us  the  feeling  of 
familiarity. 

There  are  also  feelings  of  familiarity  associated  with  our 
perceptions:  they  occxu"  when  the  same  thing  is  seen  or  heard 
repeatedly.     On  returning  to  a  town  after  an  absence  the 


184  MEMORY  AND  IMAGINATION      [ch.  vra 

place  looks  familiar.  We  recognize  our  friends  because  we 
are  familiar  with  their  features.  Certain  tunes  are  familiar 
because  we  have  heard  them  over  and  over  again.  Even  a 
stranger  may  look  familiar  to  us  because  he  resembles  some 
one  we  know.  In  all  such  cases  the  feeling  of  familiarity  is 
due  to  the  traces  of  similar  past  experiences  which  unite 
with  the  present  impression.  The  perception  process  is 
easier  because  of  these  traces.  Recognition  depends  on  ease 
q[_nsrw2is^cgndiiction.  In  recognizing  persons  we  may  not 
recall  definitely  any  incident  connected  with  them;  the 
familiarity  feeling  in  perception  is  merely  a  vague  memory 
element  added  to  the  sensations  which  make  up  the  percep- 
tion. 

Recollection.  —  Memory  images  are  aroused  by  nerve 
impulses  passing  into  some  brain  center  and  taking  the  form 
of  the  traces  which  have  been  left  in  that  center.  The  result 
is  that  we  have  an  experience  resembling  a  former  perception; 
we  remember  or  recall  the  past  experience.  The  question 
remains,  why  we  recall  one  incident  rather  than  another. 
A  little  while  ago  some  one  spoke  of  Paris,  and  I  immedi- 
ately remembered  standing  on  the  corner  of  the  Rue  de  la 
Paix  last  summer  looking  at  the  Vendome  Column.  Why 
was  that  particular  scene  recalled,  rather  than  some  other 
part  of  the  city? 

The  real  explanation  is  that  the  nerve  impulse  which 
arouses  the  recollection  passes  into  one  center  rather  than 
another  because  the  resistance  is  less  in  that  direction;  and 
the  degree  of  resistance  is  determined  by  the  amount  of 
retention,  fatigue,  and  other  nervous  conditions.  We  can- 
not study  these  nervous  conditions  in  the  brain  directly,  but 
we  can  observe  their  results  by  examining  our  own  experiences. 
We  can  notice  what  sorts  of  memories  are  aroused  by  various 
sorts  of  perceptions  and  other  memories.  This  study  has  led 
to  the  formulation  of  certain  fundamental  principles  which 
are  called  the  laws  of  associaiion,  because  the  most  impor- 


CH.  vm]  RECOLLECTION  185 

tant  thing  in  recollection  is  successive  association  or  sug- 
gestion. 

The  discovery  of  the  laws  of  association  was  one  of  the 
earliest  accomplishments  of  psychology.  Aristotle,  the 
father  of  the  human  sciences,  took  up  the  problem  nearly 
2300  years  ago  and  concluded  that  association  proceeds 
according  to  three  principles :  Similarity,  Contrast,  and  Con- 
tiguity; that  is  to  say,  a  perception  or  idea  calls  up  an  idea  of 
something  which  either  resembles  it,  or  is  in  striking  contrast 
with  it,  or  was  formerly  near  it  in  time  or  space.  Since  Aris- 
totle's time  it  has  become  evident  that  contrast  is  not  a  real 
principle  of  association.  Black  does  not  suggest  white  much 
more  readily  than  it  does  blue;  any  color  may  suggest  any 
other  through  general  similarity  —  because  they  are  all  colors. 
A  giant  does  not  suggest  a  dwarf  unless  we  have  seen  a  giant 
and  a  dwarf  together,  and  this  is  a  case  of  contiguity. 

The  two  remaining  principles,  Similarity  and  Contiguity, 
have  been  confirmed  as  fundamental  laws  of  association. 
Memories,  imaginations,  and  thoughts  are  aroused  either  (1) 
through  their  resemblance  to  what  we  are  perceiving  or  think- 
ing about  at  the  time,  or  (2)  through  having  been  previously 
a  part  of  some  similar  experience  or  closely  connected  with  it. 

When  you  see  a  stranger  and  are  reminded  of  some  one  you 
know,  it  is  because  the  stranger  looks  like  your  friend  or  acts 
like  him  —  similarity.  When  you  hear  the  name  of  Abraham 
Lincoln  and  think  of  the  Emancipation  Proclamation  it  is 
because  the  two  ideas  have  been  closely  connected  together 
before.  The  thought  of  Paris  led  me  immediately  to  remem- 
ber the  Vendome  Column,  because  the  Column  was  part  of 
my  former  experiences  of  Paris. 

Contiguity  and  similarity  are  not  independent  principles: 
they  work  together.  The  stranger  resembles  your  friend;  but 
when  you  recall  your  friend,  yoiu"  memory  picture  includes 
some  features  in  which  he  is  unlike  the  stranger.  These  are 
recalled  by  contiguity.    It  is  more  exact,  then,  to  regard  the 


186  MEMORY  AND  IMAGINATION      [ch.  vin 

law  of  similarity  and  contiguity  as  a  single  principle,  though 
usually  one  of  the  two  factors  is  more  prominent  than  the 
other. 

Law  of  Similarity  and  Contiguity:  An  experience  tends 
to  recall  another  experience  which  resembles  it  in  part,  the 
dissimilar  elements  being  such  as  were  closely  connected 
with  that  other  experience  in  space  and  time. 

We  have  still  not  answered  fully  the  question  raised  at  the 
outset  —  why  this  particular  memory  or  thought  is  aroused 
rather  than  one  of  a  dozen  others.  Many  persons  you  know 
are  more  or  less  like  the  stranger  —  why  do  you  recall  just 
this  one  of  your  friends?  You  have  heard  of  many  things 
connected  with  Lincoln.  Why  do  you  recall  the  Proclama- 
tion? The  law  of  similarity  and  contiguity  does  not  explain 
the  facts  completely.  It  must  be  supplemented  by  certain 
other  principles,  which  are  called  quantitative  laws  of  associa- 
tion. There  are  three  important  quantitative  laws  which 
determine  the  selection  of  ideas:  frequency,  vividvess,  and 
recency. 

(1)  Law  of  Frequency:  An  experience  which  has  been 
repeated  many  times  tends  to  be  recalled  as  a  memory  or 
thought  more  readily  than  an  experience  which  has  occurred 
in  the  past  only  once  or  a  few  times. 

We  recall  the  name  or  looks  of  a  friend  much  more  readily 
than  we  recall  a  stranger.  The  same  law  holds  for  verbal 
memory;  we  tend  to  recall  far  more  readily  phrases  we  have 
memorized  than  those  we  have  heard  only  a  few  times.  The 
law  may  be  explained  in  terms  of  nerve  activity:  Repetition 
improves  the  synaptic  connections  between  neurons,  and 
this  facilitates  thereafter  the  passage  of  nerve  impulses  along 
the  same  path. 

(2)  Law  of  Original  Vividness:  Among  alternative  ideas, 
any  one  of  which  might  be  recalled,  that  particular  one  tends 
to  be  suggested  which  was  more  intense  or  vivid  when  it 
occurred  originally  as  a  perception  or  thought. 


CH.  viii]  RECOLLECTION  187 

We  tend  to  recall  more  readily  an  important  or  thrilling 
experience  than  one  which  we  did  not  attend  to;  vivid 
thoughts  and  clean-cut  phrases  are  most  apt  to  be  recalled. 
The  explanation  is  that  an  intense  nerve  impulse  tends  to 
leave  a  deeper  trace  in  the  neurons  through  which  it  passes, 
and  this  makes  these  neurons  more  fit  to  receive  future 
impulses. 

(3)  Law  of  Recency:  A  recent  experience  is  more  apt  to  be 
recalled  than  an  experience  which  occurred  some  time  ago. 

We  recall  many  more  events  of  the  past  week  than  occur- 
rences dating  back  a  year  or  ten  years.  This  is  because  a 
nervous  path  which  has  recently  been  used  is  more  passable 
than  paths  which  have  not  been  used  for  a  long  period  of  time. 
Connections  in  the  central  nervous  system  tend  to  become 
more  resistant  through  disuse. 

The  factors  of  frequency,  vividness,  and  recency  often  con- 
flict. A  vivid  experience  which  occurred  many  years  ago  may 
be  recalled  more  readily  than  a  recent  experience  of  lesser 
vividness.  Frequent  repetition  may  strengthen  a  remote 
experience.  On  the  other  hand  an  experience  which  has 
never  been  attended  to  —  which  lacks  vividness  —  may  not 
be  recalled  even  though  it  has  been  repeated  many  times.  We 
all  know  how  hard  it  is  to  remember  a  set  of  instructions  on  a 
subject  which  is  entirely  outside  our  interests,  no  matter 
how  often  they  are  drummed  into  us. 

Forgetting. — Why  do  we  fail  to  remember  certain  things  — 
especially  proper  names  —  though  we  try  our  best  to  recall 
them?  Often  when  you  start  to  speak  about  some  one  whom 
you  know  perfectly  well,  you  suddenly  find  you  are  unable  to 
recollect  his  name.  You  cannot  recall  whether  you  locked 
the  door  or  turned  off  the  light  downstairs.  You  put  a  paper 
away  very  carefully  for  future  use;  and  now  you  have  not  the 
slightest  idea  where  you  put  it.  You  make  a  dinner  engage- 
ment two  days  ahead:  when  the  time  comes  you  forget  it. 

In  the  case  of  proper  names  there  is  often  a  vain  struggle  to 


188  MEMORY  AND  IMAGINATION      [ch.  vin 

remember.  We  think  of  several  names  one  after  the  other, 
and  reject  each  in  turn,  recognizing  at  once  that  it  is  not  the 
right  one;  —  it  lacks  the  feeling  of  familiarity.  Sometimes 
we  go  down  the  alphabet  systematically,  trying  out  each 
letter  in  turn,  and  perhaps  strike  the  right  word  as  a  matter  of 
chance.  The  attempt  to  recall  a  man's  name  by  picturing 
how  he  looks  is  generally  futile.  If  we  dismiss  the  subject 
completely  it  often  happens  that  the  desired  name  suddenly 
*  jumps  up  in  consciousness  '  —  it  may  be  in  a  minute  or 
within  an  hour,  or  perhaps  only  after  several  days. 

The  subject  of  forgetfulness  has  not  been  studied  so  thor- 
oughly as  memory  and  recollection.  But  the  following  prin- 
ciples have  been  noticed :  they  apply  not  merely  to  names  but 
to  memory  lapses  of  all  sorts. 

(1)  Conflicting  Associations:  If  another  thought,  simi- 
lar to  the  one  we  are  trying  to  recall,  is  present,  it  tends  to  fix 
the  attention  and  exclude  the  desired  thought.  This  ac- 
counts for  most  cases  of  inability  to  recall  names.  I  cannot 
recall  the  name  of  my  Latin  professor.  Dr.  Packard.  The 
name  of  Dr.  Patton  has  come  up  first  and  holds  the  field, 
preventing  the  other  association.  I  meet  an  old  acquaint- 
ance after  several  years  and  am  at  a  loss  for  his  name;  I  can 
only  think  of  Lamson  —  not  because  the  name  sounds  like 
Lamson  but  because  the  man  looks  like  Lamson,  whom  I 
have  seen  more  recently. 

(2)  Faintness:  If  an  experience  was  not  originally  at- 
tended to,  or  is  not  recent,  or  has  not  been  repeated,  it  is 
difficult  to  recall  it.  You  do  not  remember  whether  you  have 
locked  the  door  because  the  action  was  quite  automatic; 
you  did  not  pay  attention  to  it.  You  forget  where  the  paper 
was  laid  away,  because  the  occurrence  took  place  some  time 
ago.  In  a  city  we  pass  many  people  daily  on  the  street;  if 
we  chance  to  pass  one  of  them  a  second  time  we  fail  to  recog- 
nize him  unless  there  is  something  striking  about  his  appear- 
ance —  that  is,  unless  the  original  impression  was  vivid. 


CH.  VIII  ]  FORGETTING  189 

This  law  of  faintness  is  simply  the  negative  side  of  our  three 
laws  of  recall. 

(3)  Inhibition:  If  an  experience  is  painful  or  is  accom- 
panied by  some  unpleasant  emotion,  the  recollection  tends  to 
be  inhibited.  If  you  have  done  something  you  are  ashamed 
of,  every  time  you  recall  it  you  dismiss  it  from  thought  by 
passing  as  quickly  as  possible  to  something  else.  In  this  way 
the  tendency  to  recall  this  particular  thing  is  continually 
weakened  till  at  last  the  association  may  be  entirely  inhib- 
ited. Some  writers  describe  this  as  a  *  repression '  of  un- 
pleasant ideas  into  the  subconscious  field.  The  process  is 
really  not  a  repression  but  a  weakening  or  inhibition  of 
associations. 

The  influence  of  frequency  and  recency  on  the  rate  of  for- 
getting may  be  studied  experimentally  by  committing  to 
memory  several  series  of  nonsense  syllables.  Meaningless 
syllables  do  not  differ  in  vividness  like  words,  so  that  one 
series  makes  the  same  impression  on  you  as  another.  If  you 
take  two  different  nonsense  series,  and  repeat  one  a  great 
many  times  and  the  other  only  two  or  three  times,  you  find 
that  very  much  more  of  the  former  is  retained.  If  you  repeat 
several  nonsense  series  the  same  number  of  times  and  try 
to  recall  one  after  one  day,  another  after  two  days,  and  so 
on,  you  can  determine  how  much  you  forget  as  time  goes 
on.  This  is  shown  in  Fig.  69.  The  curves  (which  repre- 
sent the  amount  retained)  drop  decidedly  at  first,  and  less 
and  less  thereafter.  In  other  words,  the  amount  of  loss  is 
greatest  at  first;  and  there  is  less  additional  loss  as  time 
goes  on. 

It  is  often  asked  whether  any  experience  is  really  forgot- 
ten—  whether  all  traces  in  the  brain  substance  persist 
indefinitely,  or  if  some  wear  away  completely  in  the  course 
of  time.  Instances  are  cited  of  events  in  early  life  which  are 
recalled  after  an  interval  of  many  years.  In  two  cases 
recently  reported,  men  of  ninety  repeated  orations  which 


190 


MEMORY  AND  IMAGINATION      [ch.  viii 


they  had  learned  in  boyhood  and  had  apparently  not  recalled 
meanwhile.  In  both  these  cases  the  lines  were  originally 
fixed  in  memory  by  repetition  (and  interest),  so  that  the 


Fig.  69.  —  Cubve  of  Forgetting 

The  curves  show  the  results  of  experiments  on  learning  and  forgetting  by 
three  different  investigators.  A  and  B  memorized  nonsense  syllables.  C  used 
series  of  jumbled  letters.  The  curves  show  the  percentage  recalled  after  various 
time  intervak.     [After  Starch.] 


recollection  was  not  the  revival  of  an  isolated  experience. 
James  cites  the  case  of  a  very  young  woman  who  could 
neither  read  nor  write,  who  during  a  fever  uttered  sentences 
in  Latin,  Greek,  and  Hebrew  —  languages  with  which  she 
was  wholly  unfamiliar.  It  was  found  that  during  her  child- 
hood she  lived  in  the  family  of  an  old  clergyman,  who  was 
accustomed  to  walk  up  and  down  reading  aloud  in  these  Ian- 


CH.  vra]  FORGETTING  191 

guages.  Passages  repeated  by  the  woman  were  found  in 
books  from  his  Ubrary.  The  impressions  had  been  retained 
many  years  without  either  repetition  or  original  vividness. 

Whether  any  memory  is  utterly  lost  is  uncertain.'  It  is 
safe  to  say  that  far  more  is  retained  than  we  ever  actually 
recall.  It  may  be  that  in  the  normal  brain  every  trace  per- 
sists indefinitely.  Or  it  may  be  that  the  traces  wear  away,  or 
are  gradually  effaced  by  other  traces.  Too  little  is  known  at 
present  about  the  nature  of  memory  traces  to  answer  the 
question  definitely. 

Training  the  Memory.  —  The  practical  value  of  a  good 
memory  is  too  obvious  to  need  discussion.  One  of  the  most 
frequent  questions  put  to  the  psychologist  by  outsiders  is: 
Can  you  help  me  to  improve  my  memory?  A  good  memory 
means  ability  to  recall  what  we  want  when  we  want  it.  This 
depends  on  several  different  factors:  (1)  perception;  (2)  the 
learning  process;  (3)  verbal  association. 

(1)  Perception:  Certain  sorts  of  memory  depend  essen- 
tially on  accurate  perception,  and  the  obvious  way  to  improve 
them  is  to  train  our  perceptions.  The  memory  for  faces  is  a 
good  example  of  this.  Contrast  the  man  who  recognizes  at  a 
glance  a  person  whom  he  has  not  seen  for  years,  with  the  man 
who  is  always  in  doubt  as  to  the  identity  of  the  people  he 
meets.  The  one  has  been  accustomed  from  childhood  to 
perceive  faces  accurately;  recollection  takes  place  automati- 
cally. The  other  has  never  trained  himself  to  observe  faces 
carefully.  Often  the  deficiency  is  due  to  defective  eyesight. 
Near-sighted  and  astigmatic  persons  do  not  see  faces  clearly; 
they  cannot  recall  them  because  they  have  never  registered 
the  distinguishing  marks.  Such  persons  may  recognize  a 
man  instantly  by  the  tone  of  his  voice. 

Another  sort  is  the  memory  for  scenes  and  incidents.  We 
often  wish  to  describe  scenes  or  events  to  friends  —  some- 

^  If  one  of  the  brain  centers  is  destroyed  by  disease  or  accident,  the  traces 
in  that  center  are  gone,  and  with  them  the  possibility  of  certain  recollections. 


192  MEMORY  AND  IMAGINATION      [ch.  vm 

times  we  are  asked  to  testify  about  them  in  court.  Accurate 
testimony  depends  on  accurate  perception.  The  witness  who 
told  of  a  man  "  pacing  to  and  fro,  his  hands  behind  his  back, 
reading  a  newspaper,"  must  have  observed  rather  carelessly. 
It  may  be  of  life-and-death  importance  to  recall  which  of  two 
shots  was  fired  first.  In  thrilhng  moments  accurate  percep- 
tion is  diflScult.  The  discrepancies  between  the  testimony  of 
witnesses  is  often  due  to  the  disturbances  of  perception 
wrought  by  the  excitement  of  the  moment;  it  is  no  reflection 
on  their  sincerity  or  mental  ability.  Nevertheless  a  careful 
training  of  perception  will  prevent  many  errors. 

(2)  Leabning  Process:  Memorizing  poetry  and  speeches 
so  that  we  can  repeat  them  accurately  depends  on  the  learn- 
ing process  (ch.  xi).  It  is  not  a  matter  of  accurate  perception, 
but  of  repeating  the  words  over  and  over  so  as  to  strengthen 
the  retention  traces  in  the  brain  centers.  The  ability  to 
memorize  quickly  is  largely  a  matter  of  inheritance;  that  is  to 
say,  the  inherited  nervous  system  of  some  persons  is  such  that 
they  readily  retain  long  series  of  impressions  and  reproduce 
them  in  the  right  order.  But  our  inherited  capacity  may  be 
strengthened  by  training  and  impaired  by  disuse.  Self- 
confidence  is  an  important  factor  here.  If  you  feel  sure  you 
will  succeed,  many  slips  are  avoided  which  would  occur  if  you 
distrust  yoiu"  own  ability  to  repeat  a  speech. 

(3)  Verbal  Association:  The  ability  to  recall  names 
depends  largely  on  verbal  associations.  The  names  of  com- 
mon objects  are  learned  early  in  life;  through  constant  repeti- 
tion the  word  table  becomes  an  integral  part  of  our  perception 
and  thought  of  a  table.  The  normal  man  finds  no  difficulty 
here.  It  is  the  memory  for  proper  names  that  troubles  him. 
Henry  Brown  may  have  light  hair  or  black  hair  —  the  associ- 
ation of  the  word  brown  with  the  man  Brown  is  arbitrary. 
We  meet  the  same  difficulty  in  learning  a  foreign  language 
unless  the  words  are  similar  to  our  own.  The  French  word 
jromage  is  difficult  to  associate  with  cheese. 


CH.  viii]  TRAINING  THE  MEMORY  19S 

Language  is_a  higher  mentaLprocess  than  perception  and 
imageiyT''  The  understanding  of  words  involves  brain 
centers  at  a  higher  nervous  level  than  the  perception  centers. 
The  act  of  associating  words  with  perceptions  (or  with  mental 
images)  is  different  from  ordinary  association;  it  follows  much 
the  same  principles,  but  it  is  a  more  specialized  process. 
Verbal  memory  may  be  improved  to  some  extent  by  training. 
In  old  age  it  is  the  first  to  deteriorate;  witness  the  struggles  of 
elderly  persons  to  recall  the  names  of  their  best  friends  and 
even  of  their  own  children. 

Statistical  data  belong  in  the  same  class.  The  date  of  the 
discovery  of  America,  the  rate  at  which  sound  travels  through 
the  air,  the  population  of  Chicago,  are  arbitrary  associations 
of  numbers  with  events  or  objects.  Much  of  our  scientific 
knowledge  is  of  this  sort.  There  are  certain  facts  that  "  every 
educated  man  ought  to  know."  How  far  to  insist  on  such 
knowledge  is  a  serious  problem.  Teachers  are  inclined  to 
attach  undue  importance  to  this  kind  of  memory.  Ency- 
clopedias and  reference  books  are  generally  available,  and  it 
seems  useless  to  burden  the  child's  memory  unnecessarily. 
He  should  of  course  be  taught  the  addition  and  multiplication 
tables,  weights  and  measures,  and  other  fundamental  statisti- 
cal matters.  But  in  the  higher  education  it  seems  more  im- 
portant to  teach  the  student  where  to  look  for  information  than 
to  take  up  his  time  in  memorizing  arbitrary  number  associar 
tions. 

Certain  devices  have  been  invented  to  assist  this  sort  of 
memory.  The  figures  are  associated  with  letters  of  the  alpha- 
bet (consonants),  and  a  catch-phrase  is  made  up  which  brings 
together  the  number  and  the  fact.  Let  b=l,  g=4,  r=9, 
d  =  2;  then  the  number  1492  is  represented  by  b,  g,  r,  d.  We 
invent  the  phrase,  "  Columbus  made  a  big  raid  on  America," 
and  thus  remember  the  date.  Many  persons  find  such  a 
system  useful;  others  find  they  get  on  quite  as  well  without  it. 
^  See  ch.  xiiL 


194  MEMORY  AND  IMAGINATION      [ch.  vm 

There  is  danger  of  course  that  the  phrase  may  be  twisted. 
If  we  think  that  Columbus  made  a  *  bad  raid,'  the  discovery 
of  America  would  be  shifted  to  1292. 

Imagination  (Fancy).  — An  imaginaiion  image  or  fancy  is 
an  image  composed  of  elements  from  two  or  more  separate 
experiences.  A  typical  example  is  our  mental  picture  of  a 
centaur,  which  combines  the  head  and  arms  of  a  man  with  the 
body  and  legs  of  a  horse.  This  image  is  a  combination  of  two 
separate  perceptions  —  unless  it  happens  to  be  the  memory 
of  some  picture  or  statue  we  have  seen.  The  scenes  in  a  novel 
or  history,  as  we  mentally  picture  them,  are  imagination 
images.  We  piece  together  bits  from  familiar  experiences 
suggested  by  the  narrative,  and  construct  scenes  which  may 
be  quite  different  from  anything  we  have  ever  witnessed. 
The  plans  of  an  inventor  in  the  earlier  stages  are  imagination 
images;  they  are  pictures  based  on  real  experiences,  but  are 
unlike  anything  the  inventor  has  actually  perceived. 

Some  of  our  fancies  are  so  fantastic  that  we  are  apt  to 
regard  them  as  absolutely  different  from  our  perceptions. 
This  is  not  the  case.  The  elements  composing  the  image  are 
often  much  transformed  from  the  original,  but  they  are 
always  derived  from  former  sensations  of  some  sort.  On  the 
other  hand  it  does  not  follow  that  every  fancy  represents 
some  reality  or  possible  reality.  An  imagination  image  is 
novel  in  just  the  same  way  that  an  invention  is  novel.  The 
finished  product  is  new,  but  not  the  materials. 

The  practical  working  of  imagination  will  be  better  under- 
stood if  we  study  its  manifestations  in  children,  before  it  has 
been  overlaid  with  higher  processes  of  thought  and  molded 
into  definite  lines  by  our  interests  in  life.  The  child  is  natur- 
ally imaginative.  He  pictures  the  fairies  and  monsters  of 
his  story  books  vividly.  He  hears  animals  talk,  he  sees  inani- 
mate things  acting  like  living  creatures  —  all  this  as  dis- 
tinctly as  though  the  experiences  were  actually  remembered. 
There  seems,  in  fact,  to  be  no  sharp  distinction  in  early  lif#" 


CH.  viii]         NATURE  OF  IMAGINATION  195 

between  memory  and  imagination.  The  child  tells  of  imagi- 
nary adventures  with  the  same  sense  of  reality  that  he  feels  in 
describing  real  occurrences.  Many  of  the  child's  lies  have  no 
ethical  significance  whatsoever,  —  though  their  psychological 
significance  may  be  most  important,  as  indicating  the  nature 
of  his  mental  processes. 

These  facts  indicate  that  in  early  childhood  imagination  is 
as  fundamental  as  memory.  Both  depend  on  retention  and 
revival.  Memory  is  revival  of  definite  groups  of  retention 
traces,  while  imagination  is  the  revival  of  separate  traces 
which  are  grouped  together  into  new  experiences.  It  appears 
that  imagination  is  really  not  distinguished  from  memory  in 
early  childhood.  This  is  probably  because  memory  traces 
are  not  yet  deeply  fixed,  so  that  the  revival  is  not  accom- 
panied by  a  strong  familiarity  feeling. 

As  the  child's  mind  develops,  the  distinction  between 
memory  and  imagination  grows  more  definite.  Memory 
images  are  recognized  as  such  by  the  accompanying  familiar- 
ity feeling  and  by  their  setting  in  space  and  time.  The  dis- 
tinction is  fostered  socially  by  the  punishment  or  disapproval 
which  follows  when  the  child  tells  as  fact  what  really  belongs 
to  the  realm  of  imagination.  The  outer  world  becomes  to 
him  more  and  more  an  independent  reality;  his  memories 
represent  that  real  world,  and  his  fancies  do  not. 

As  we  pass  out  j)f^  childhood  the  imagination  tends  to 
become  more  restricted.  Instead  of  being  free  and  desultory 
it  falls  into  certain  definite  grooves.  In  one  person  it  tends 
toward  artistic  creation,  in  another  toward  invention;  one 
man  seeks  to  explain  the  mysteries  of  nature,  another  pro- 
poses to  reorganize  society.  In  this  way  various  types  of 
imagination  arise,  based  on  the  special  life  interests  of  the 
individual.  Esthetic,  creative,  scientific,  and  social  or  ethical 
imagination  are  broad  general  types;  under  them  we  find 
many  subordinate  types,  such  as  pictorial,  musical,  and 
graphic  imagination. 


196  MEMORY  AND  IMAGINATION      [ch.  vin 

Other  Kinds  of  Imagery.  —  Besides  memory  and  fancy 
there  are  several  other  sorts  of  images.  Anticipations  are 
images  which  pictm'e  our  future  actions  and  lead  to  some 
appropriate  activity  on  our  part.  Both  voluntary  and  invol- 
untary acts  may  be  preceded  by  anticipation  images.  My 
mental  picture  of  a  ball  game  scheduled  for  this  afternoon 
leads  me  to  walk  down  to  the  field.  The  nerve  impulses 
concerned  in  this  image  are  part  of  the  set  of  operations  in  the 
nervous  system  which  start  the  appropriate  movements. 

Anticipation  images  are  similar  to  fancies  except  for  their 
'  prospective  reference.'  A  fancy  may  suddenly  blossom  into 
an  anticipation  —  when  the  painter  starts  to  paint  or  the 
inventor  begins  to  build  his  machine;  an  anticipation  image 
withers  into  mere  fancy  when  our  plans  fail. 

There  are  two  reasons  for  emphasizing  anticipation  as  a 
distinct  sort  of  image.  First,  because  it  is  intimately  con- 
nected with  our  active  life.  Anticipation,  or  purpose,  is  more 
efficient  than  imagination  in  bringing  about  suitable  re- 
sponses; and  this  after  all  is  the  vital  point  in  mental  life. 
Second,  the  anticipation  image  arose  earlier  in  animal  evolu- 
tion and  appears  earlier  in  the  human  child  than  fancy. 
Image  experiences  seem  to  have  arisen  in  the  first  place  as  a 
method  of  reaching  into  the  future,  not  as  a  means  of  bring- 
ing back  the  past  or  of  picturing  novelties.  When  a  baby 
cries  for  milk,  he  has  probably  a  faint  anticipation  of  getting 
it.  The  dog  who  jumps  about  when  his  master  appears  in 
hunting  costume  would  seem  to  have  a  rather  vivid  anticipa- 
tion of  what  is  going  to  happen. 

A  composite  image  ^  is  built  up  through  frequent  repetitions 
of  substantially  the  same  experience.  It  is  a  more  perfect 
reproduction  of  past  experiences  than  an  imagination,  but  it 
is  less  definite  than  a  memory.  The  effect  of  this  repetition 
is  to  weaken  the  general  setting,  which  is  different  in  each 
case.  The  image  represents  some  object  we  have  actually 
1  Also  called  a  free  imoffe. 


CH.  vin]        OTHER  KINDS  OF  IMAGERY  197 

perceived,  but  it  shows  the  object  without  any  definite  loca- 
tion in  time  and  space  and  with  no  fixed  surroundings  or 
background.  You  often  picture  the  face  of  a  friend  or  a 
famiHar  tune  without  special  reference  to  time  or  place  or 
circumstances;  the  image  is  a  composite  effect  of  many  past 
experiences.  The  repetition  strengthens  the  accompanying 
feeling  of  familiarity,  and  usually  adds  something  to  the  image 
itself.  The  composite  image  of  your  friend's  face  usually 
includes  both  profile  and  full  front  views,  and  the  composite 
image  of  a  house  may  include  both  inside  and  out,  which  we 
never  perceive  or  recall  in  the  same  picture. 

A  general  image  is  due  to  the  fusion  of  many  similar  images 
into  a  single  experience.  It  arises  from  the  perception  of  a 
number  of  objects  which  are  partly  similar  and  partly  unlike. 
When  the  child  has  seen  a  number  of  men  whose  general 
appearance  is  the  same,  but  with  certain  differences,  he 
begins  to  form  a  mental  image  which  embraces  their  common 
features.  These  common  points  are  vivid,  and  make  up  the 
focus  of  the  image;  the  details  in  which  men  differ  appear 
only  indistinctly  in  the  margin  of  the  conscious  field.  In  the 
same  way  the  child  forms  a  general  image  of  a  horse  and  of 
various  other  sorts  of  creatures  and  objects. 

Our  general  image  of  horse  in  adult  life  is  probably  based 
on  memories  of  a  certain  horse  —  it  may  be  an  old  bay  mare 
we  knew  in  childhood.  Attached  to  this  memory  are  a 
variety  of  different  characteristics,  such  as  gray  and  black, 
long-tailed  and  bobtail,  stocky  and  sUm,  derived  from  our 
experiences  of  other  horses.  These  points  of  difference  be- 
tween horses  are  only  faintly  pictured  in  the  general  image, 
while  the  characteristics  common  to  all  horses  are  empha- 
sized. In  other  words,  our  general  image  of  the  horse,  though 
based  upon  some  particular  animal,  is  not  stocky  nor  sHm, 
it  has  no  distinctive  color,  no  special  trim  of  the  tail;  many 
of  the  features  and  outlines  are  vague.  The  prominent 
elements  in  the  general  image  are  those  details  in  which  all 


198  MEMORY  AND  IMAGINATION      [ch.  viii 

horses  agree,  and  which  distinguish  horses  from  other  crea- 
tures. 

In  adult  Hfe  the  general  image  rarely  occurs  in  a  pure  form; 
almost  always  a  word  or  symbol  of  some  sort  attaches  to  it, 
and  it  becomes  a  thought  (ch,  xiii).  Thought  is  a  higher  type 
of  experience  than  the  general  image. 

Illusions  of  Memory  and  Hallucinations.  —  We  often  make 
mistakes  in  interpreting  our  image  experiences,  just  as  we 
make  mistakes  in  perception.  Two  different  sorts  of  errors 
occur  in  connection  with  imagery :  illusions  of  memory,  and 
hallucinaiions. 

Illusions  of  memory  are  due  to  our  misinterpreting  some 
factor  in  the  experience.  The  most  common  illusion  is  based 
on  the  *  location  '  factor.  If  the  memory  of  an  event  includes 
only  a  few  details  it  is  easy  to  refer  it  to  the  wrong  time  or 
place.  I  recall  a  conversation  with  a  friend;  the  surround- 
ings are  not  definitely  recalled,  and  I  imagine  it  occurred  when 
we  met  in  New  York;  actually  the  discussion  took  place  at 
another  meeting  elsewhere. 

It  often  happens  that  the  memory  of  a  certain  event  re- 
mains unusually  vivid,  so  that  we  place  it  much  too  near  the 
present  time.  The  opposite  is  true  when  we  move  to  a  new 
town  and  quickly  grow  familiar  with  our  surroundings.  We 
soon  get  the  feeling  that  we  have  lived  there  a  long  time; 
the  older  background  tends  to  fade  into  the  distance. 

Another  illusion  consists  in  mistaking  an  imagination  for  a 
memory.  I  remember  distinctly  posting  a  certain  letter,  and 
assure  my  wife  I  did  so.  When  the  letter  turns  up  later  in  my 
overcoat  pocket  the  '  memory  '  proves  to  have  been  merely  a 
vivid  imagination.  Usually  this  sort  of  illusion  is  due  to  the 
mingling  of  imagination  elements  in  a  memory  picture.  I 
remembered  taking  the  letter  but  I  imagined  the  post-box 
part.  The  inaccuracies  of  court  testimony  are  often  to  be 
explained  in  this  way.  You  describe  a  man  in  a  brown  suit 
and  a  derby  hat.    Your  description  is  correct  except  that  the 


CH.  viii]  ILLUSIONS  OF  MEMORY  199 

suit  was  gray  and  he  wore  no  hat.  These  details  were  added 
(quite  innocently)  from  the  imagination. 

Such  illusions  are  often  due  to  the  fact  that  you  first 
imagine  certain  details  and  then  remember  your  imagination. 
Who  has  not  related  incidents  of  family  history  that  have 
been  handed  down  through  the  years,  and  felt  certain  he 
witnessed  them?  —  only  to  discover  that  they  occurred  some 
time  before  he  was  born.  They  are  memories  indeed,  but 
memories  of  narratives  that  have  been  told  him  —  memories 
of  the  vivid  fancies  which  he  formed  on  hearing  the  stories  in 
childhood. 

An  illusion  is  the  wrong  interpretation  of  certain  factors  or 
eleme^nts  in  the  experience.  An  hallucination  is  the  confusion 
of  images  or  thoughts  with  perceptions. 

We  have  usually  no  diflSculty  in  distinguishing  images  and 
thoughts  from  perceptions.  One  distinguishing  mark  is 
intensity.  Most  mental  images  are  far  less  intense  than  any 
perception.  You  know  that  the  table  before  you  is  real; 
the  experience  is  too  intense  to  be  due  to  anything  but  an 
external  stimulus,  and  consequently  the  experience  is  a  per- 
ception; you  know  just  as  certainly  that  the  tune  '  running 
through  your  head  '  is  imagined;  it  is  far  weaker  than  real 
music. 

Another  factor  which  enables  us  to  distinguish  perceptions 
from  fancies  is  that  perceptions  are  independent  of  our  control. 
They  come  and  go  according  to  their  own  sweet  will  —  not  as 
we  wish.  If  we  can  call  up  or  alter  a  certain  experience  at 
will,  we  class  it  as  a  memory  or  fancy. 

These  two  factors,  intensity  and  controllability,  generally 
cooperate,  and  prevent  hallucinations.  But  they  are  not 
infallible  tests.  Some  perceptions  are  faint  and  some  fancies 
are  vivid.  On  dark  nights  we  are  not  certain  what  we  actu- 
ally perceive  and  what  we  merely  imagine.  Dreams  are  vivid 
fancies;  for  the  time  being  they  appear  to  be  perceptions, 
since  we  have  no  external  sensations  to  compare  them  with. 


jSOG  MEMORY  AND  IMAGINATION      [ch.  vm 

In  states  of  high-strung  tension  one  sees  a  specter,  or  hears 
voices  warning  him,  though  the  experiences  are  mere  fancies. 

If  the  object  seems  to  act  independently  of  our  control,  the 
error  may  be  reinforced,  or  our  uncertainty  may  be  greater. 
In  such  cases  the  normal  individual  falls  back  upon  a  third 
test,  the  uniformity  and  general  consistency  of  experience. 
We  convince  ourselves  that  the  *  specter '  is  imagined,  that 
the  '  voice '  is  within  us,  because  such  experiences  do  not 
conform  to  the  general  scheme  of  things.  Even  in  dreams  we 
sometimes  notice  the  inconsistency  of  the  experience  with 
other  circumstances  and  realize  that  we  are  asleep. 

The  characteristics  by  which  we  distinguish  imagination 
from  perception  are  merely  practical  tests,  based  upon  the 
general  run  of  our  experiences.  In  most  cases  there  is  a  sharp 
dividing  line  between  them,  and  the  bulk  of  our  experiences 
fall  naturally  into  one  class  or  the  other.  But  neither  the 
experience  itself  nor  its  elements  furnish  a  decisive  indication 
of  the  original  source.  Both  imagination  and  ^perception  are 
due  to  brain  processes;  either  may  readily  be  mistaken  for  the 
other  if  its  general  characteristics  fall  within  the  border-line 
territory. 

In  certain  mental  diseases  the  patient  ignores  the  test  of 
consistency,  and  systematically  mistakes  his  fancies  for 
objective  reality.  These  pathological  states  are  delusions; 
they  are  a  stage  beyond  hallucinations. 

Importance  and  Training  of  Imagery.  —  Memory  and  imag- 
ination are  of  varying  importance  in  human  life.  As  we 
advance  in  civilization  the  use  of  imagery  develops  more  and 
more  into  verbal  thinking  and  the  use  of  image  pictures  tends 
to  become  less  active.  In  certain  occupations  imagination  is 
especially  serviceable  and  deserves  cultivation.  The  *  crea- 
tor '  of  every  sort  —  whether  artist,  writer,  or  inventor  — 
is  helped  by  the  cultivation  of  exact  and  vivid  imagina- 
tion; the  professional  man,  the  scientist,  and  the  business  man 
usually  find  verbal  thinking  more  useful. 


CH.  vm]        CULTIVATION  OF  IMAGERY  201 

Nikola  Tesla,  the  inventor,  attributes  much  of  his  success 
to  his  power  of  visualizing  distinctly,  and  in  detail,  the 
machine  which  he  wishes  to  devise.  The  whole  idea  is 
worked  out  mentally  before  ever  a  sketch  is  put  on  paper. 
"  In  my  mind  I  change  the  construction,  make  improvements, 
and  even  operate  the  device."  ^ 

The  exactness  and  vividness  of  imagery  depends  largely  on 
our  ability  to  observe  our  perceptions  exactly.  The  training. 
of  perception  is  essential  to  accurate  memory  and  vivid 
imagination.  This  must  be  supplemented  by  practice  in 
recalling  events  in  detail  and  by  constant  exercise  of  the 
imagination.  The  cultivation  of  imagination  is  useful  only  in 
certain  hues  of  work;  but  memory  training  is  of  general 
utiUty. 

It  is  a  matter  of  great  social  importance  to  be  able  to 
distinguish  clearly  between  true  memories  of  objective  events 
and  mere  fancies.  Lying  has  an  ethical  significance.  It  is 
more  than  a  *  psychological  phenomenon  '  in  the  adult.  For 
this  reason  it  is  important  for  every  man  to  learn  to  distin- 
guish clearly  between  truth  and  fiction.  Fancy  as  fancy  has  a 
legitimate  place  in  mental  life.  Like  play  and  jesting  it 
relieves  the  strain  of  our  more  serious  occupations.  The  most 
earnest  mental  worker  finds  relaxation  in  pure  horse-play, 
and  the  most  rigid  logician  heartily  enjoys  a  pun.  The  atti- 
tude to  be  cultivated  is  one  of  absolute  sincerity  in  matters 
of  fact;  we  should  discriminate  clearly  between  objective 
facts  or  truths  and  the  constructions  of  our  own  imagination. 
The  more  completely  we  separate  these  two  spheres,  the 
better  can  we  appreciate  the  fantastic  tales  of  Wells  and  the 
subtle  exaggerations  of  Mark  Twain. 

Summary.  —  In  this  chapter  we  have  examined  imagery^ 

an  experience  which  owes  its  characteristics  to  brain  traces  of 

former  experiences  —  not  to  the   present  stimulus.     Most 

images  are  revivals  of  external  sensations;  though  occasion- 

*  Quoted  in  American  Mag.,  April,  1921,  p.  62. 


202  MEMORY  AND  IMAGINATION      [ch.  vin 

ally  other  kinds  of  sensations  are  revived.  The  most  impor- 
tant sorts  of  imagery  are  memory  images  and  imagination 
images  (fancies).  Memory  reproduces  some  perception  we 
have  actually  experienced;  an  imagination  is  made  up  of 
bits  of  former  perceptions,  gathered  here  and  there  and  put 
together  into  a  definite  image. 

Practical  Exercises: 

89.  Take  at  random  some  date  between  six  months  and  a  year  ago.  Try 
to  recall  as  many  incidents  as  possible  that  occurred  on  that  day. 

40.  Take  some  notable  event  in  yom-  recent  life  (over  six  months  ago)  and 
describe  the  scene  and  the  succession  of  occurrences  as  minutely  and 
accurately  as  possible. 

41.  Lying  in  bed  at  night  with  closed  eyes,  try  to  picture  imaginary  scenes 
or  stories.  Describe  the  experiences;  compare  their  vividness  with 
real  scenes;  how  far  are  they  due  to  retinal  stimulation."* 

42.  Read  a  description  of  a  scene  or  event  from  some  novel  or  history, 
and  note  the  images  which  are  aroused.  Classify  them  as  visual, 
auditory,  etc.     Grade  them  according  to  vividness. 

43.  Describe  any  experience  you  can  recall  where  you  have  mistaken  an 
imagination  for  a  perception  or  vice  versa,  or  where  you  were  unable 
to  judge  its  real  nature. 

References: 

On  memory:  H.  J.  Watt,  Economy  and  Training  of  Memory. 

On  the  rate  of  forgetting:  H.  Ebbinghaus,  Memory  (trans.). 

On  cases  of  unusual  recall:  W.  James,  Principles  of  Psychology,  I,  p.  681; 

H.  C.  Warren,  in  Psychological  Bulletin,  1918,  5,  p.  207. 
On  imagination:  F.  Galton,  Inquiries  into  Human  Faculty  (ch.  on  'Mental 

Imagery');  T.  Ribot,  Essay  on  the  Creative  Imagination  (trans.). 


CHAPTER  IX 
FEELING  AND  EMOTION 

Affective  Experiences.  —  The  experiences  we  have  exam- 
ined so  far  have  to  do  with  objects  and  conditions  outside  our 
own  body.  Perceptions  are  made  up  for  the  most  part  of 
sensations  which  come  from  the  outer  world.  Memories, 
imaginations,  and  other  images  are  made  up  chiefly  of  repro- 
ductions of  these  same  external  sensations.  Perceptions, 
images  of  all  sorts,  and  thoughts  (which  we  shall  discuss 
later)  all  belong  to  the  same  class  of  experiences,  which  are 
usually  called  cognitions  or  intellectual  experiences.  The 
responses  that  we  make  when  we  perceive  or  remember  or 
think  are  movements  which  have  to  do  with  conditions 
oiUside  us,  in  our  environment  —  not  inside  our  own  body. 

We  now  come  to  a  different  kind  of  experience  —  experi- 
ences which  are  made  up  chiefly  of  systemic  sensations  or  in 
which  systemic  sensations  are  especially  prominent.  These 
experiences  are  concerned,  first  and  foremost,  with  the  condi- 
tion of  our  bodily  organism  —  not  with  events  in  the  surround- 
ing world;  though  our  body  and  our  environment  are  too 
closely  related  to  make  the  distinction  complete.  They  are 
called  affective  experiences,  and  include  the  following  sorts: 

Feelings 

Emotions 

Sentiments 

Feeling 

Nature  of  Feeling.  —  A  feeling  is^an_eQ)erienceJii  3shich — 
sys^mic  sensations  are  the  mam  elements.'     Feelings  are 

*  Feeling  is  also  used  to  denote  any  indefinite  tensation.  This  is  an  older 
meaning  of  the  term.    It  is  still  kept,  because  the  expression  'I  sense'  has 


«04  FEELING  [ch.  ix 

made  up  of  organic  or  pain  sensations  or  both.  The  feehng 
of  hunger  which  we  experience  before  a  meal  is  due  to  organic 
sensations;  a  toothache  is  a  very  pronounced  feeling  derived 
from  the  pain  sense.  The  feeling  of  general  well-being  which 
pervades  our  body  after  a  hearty  meal  is  base'd  on  our  *  gen- 
eral sensibility  '  —  on  the  condition  of  the  body  as  a  whole. 

Systemic  sensations  have  not  only  their  own  special 
qualities  like  the  external  senses,  but  also  a  common  feeling 
tone:  they  are  either  pleasant  or  unpleasant.  When  sys- 
temic sensations  combine  into  feelings,  their  special  quaUties 
usually  fade  away  and  the  prominent  feature  is  their  pleas- 
antness or  unpleasantness. 

This  is  the  opposite  of  perception.  When  you  look  at  a 
picture  you  perceive  and  discriminate  its  various  parts;  they 
do  not  merge  together.  In  a  feeling,  the  greater  the  number 
of  sensations  entering  into  the  experience,  the  less  distinct  are 
their  details;  you  feel  more  and  more  an  indefinite  pleasant- 
ness or  unpleasantness  within  you.  A  pin-prick  is  definitely 
localized  and  stands  out  sharply.  When  you  fall  and  are 
bruised,  the  feeling  of  hurt  seems  to  spread  over  a  large  part  of 
the  body  in  an  indefinite  way.  When  you  have  a  certain 
pain  in  the  region  of  the  teeth,  you  are  not  always  sure 
whether  it  is  merely  toothache,  or  toothache  combined  with 
earache.  It  is  localized  now  in  one  place,  now  in  another. 
The  most  prominent  feature  of  these  experiences  is  the  '  hurt,' 
or  sense  of  discomfort  —  not  the  kind  of  hurt  or  its  location. 
The  same  is  true  of  pleasant  feelings.  It  is  diflScult  to  locate 
the  feehng  of  '  thrill '  or  to  analyze  its  quality. 

Our  mental  fife  at  any  moment  is  generally  tinged  with  a 
pervasive  feeling  of  some  sort.  If  the  general  tone  is  pleasant 
the  feeling  is  one  of  happiness  or  euphoria;  if  it  is  unpleasant 
the  feeling  is  despondency.     We  rarely  have  two  conflicting 

never  come  into  general  use;  but  we  must  be  careful  not  to  confuse  the  two 
meanings.  It  is  advisable  not  to  use  feeling  for  the  sense  of  touch;  this  is  too 
confusing.    The  old  English  word  'to  palp'  is  better. 


ofi.  rx]  NATURE  OF  FEELING  205 

feelings  at  the  same  time.  In  fact,  it  is  sometimes  stated  that 
pleasantness  and  unpleasantness  cannot  be  experienced 
together  at  the  same  time.  This  is  one  of  those  popular 
generalizations  which  we  must  learn  to  challenge.  Under 
some  conditions  it  is  certainly  possible  to  experience  two  con- 
flicting feelings  at  once.  We  are  pleased  when  a  friend  sym- 
pathizes with  us  over  our  toothache;  but  this  does  not  alto- 
gether obliterate  the  discomfort  of  the  ache.  In  cases  of 
this  sort  we  do  experience  both  the  unpleasant  and  the  pleas- 
ant together  —  sometimes  with  equal  vividness. 

Systemic  sensations  frequently  form  part  of  our  percep- 
tions of  external  things.  Some  odors  are  unpleasant;  most 
musical  chords  are  pleasant.  The  feeling  tone  in  such  cases 
does  not  come  directly  from  the  external  stimulus,  but  from 
some  organic  change  which  the  stimulus  brings  about.  The 
sharp  edge  of  a  knife  is  not  pain-ftd  but  jtam-inducing;  the 
pain  is  due  to  the  laceration  of  the  skin  and  the  consequent 
organic  injury.  Odors  are  unpleasant  when  they  produce 
destructive  changes  of  tissue  within  the  organism.  The 
pleasure  we  get  from  listening  to  music  is  due  to  certain 
chemical  changes  (anabolic  processes)  wrought  in  our  bodily 
system  by  the  music. 

We  may  grow  to  like  certain  odors  that  were  once  unpleas- 
ant or  to  dislike  tones  or  colors  that  were  formerly  pleasing. 
The  change  from  pleasantness  to  unpleasantness  is  due  to  the 
body  becoming  accustomed  ('  hardened  ')  to  the  stimuli,  so 
that  they  no  longer  produce  destructive  effects.  The  oppo- 
site change  is  probably  due  to  some  idea  which  works  through 
the  motor  nerves  on  the  bodily  processes.  If  "  the  very 
thought  of  that  fellow  nauseates  you,"  the  nausea  is  due  to 
nerve  impulses  from  your  brain  centers  to  the  glands  of  your 
stomach. 

Many  of  our  affwUye-expetiences  come  about  in  this 
indirect  way.  The  glands  which  secrete  the  substances  used 
in  digestion,  and  various  other  internal  glands  (including 


toe  FEELING  [cH.  ix 

those  of  the  reproductive  organs),  are  operated  by  the  auto- 
nomic nervous  system.  The  autonomic  and  cerebrospinal 
systems  work  together.  Consequently  our  feelings  often 
modify  our  ideas  and  thoughts  very  decidedly;  and  our  ideas 
often  influence  our  bodily  processes  and  produce  very  intense 
feelings.  When  a  man  is  despondent  it  is  sometimes  diflScult 
to  determine  whether  his  feeling  of  despondency  is  due  to 
certain  disturbing  thoughts,  or  his  thoughts  of  impending 
disaster  were  started  by  despondent  feelings. 

Appetite  and  Aversion.  —  Our  feelings  are  not  so  well 
developed  as  our  perceptions  and  ideas.  They  have  com- 
paratively few  different  qualities.  There  are  several  reasons 
for  this.  Systemic  sensations  are  not  so  clear-cut  and 
definite  as  the  sensations  of  sight,  hearing,  touch,  or  smell. 
They  are  produced  (except  in  the  case  of  pain)  by  internal 
stimuli  which  are  constantly  changing  and  are  difficult  to 
hold.  They  are  not  so  intimately  connected  with  conditions 
in  the  environment,  which  are  of  supreme  importance  in  the 
life  of  man. 

Our  internal  bodily  experiences  are  usually  subordinate  to 
our  experiences  of  the  world  about  us.  But  there  are  times 
when  the  organic  or  pain  stimuli  are  so  intense  or  so  insistent 
that  our  experience  is  largely  and  unmistakably  a  feeling, 
with  everything  else  in  the  background.  These  definite 
states  of  feeling  are  of  two  opposite  sorts,  appetites  and  aver- 
sions, according  as  their  general  toning  is  pleasant  or  un- 
pleasant. 

Feelings  of  appetite  result  most  frequently  from  digestive 
and  generative  sensations,  while  feelings  of  aversion  are  made 
up  of  pain  sensations  and  sensations  arising  from  disturbed 
digestive  conditions.  In  many  cases  the  tone  of  a  feeling  is 
not  pure.  The  feeling  of  digestive  appetite,  for  instance, 
includes  both  impleasant  hunger  sensations  and  pleasant 
satisfaction.  A  pain  may  be  accompanied  by  pleasant  sensa- 
tions due  to  the  healing  process.     Sometimes  the  feeling 


CH.  rs]  APPETITE  AND  AVERSION  207 

tone  is  indefinite  —  it  is  recognized  neither  as  pleasant  nor  as 
unpleasant.  Here  there  is  apparently  a  balance  between  the 
destructive  and  restorative  chemical  processes  in  the  body. 
These  neutral  feelings  are  called  excitement. 

Intense  feelings  of  any  sort  are  apt  to  arouse  activity  of 
the  muscles,  which  gives  muscle  sensations.  When  this 
occurs  the  feeling  passes  into  another  kind  of  experience, 
called  emotion.  In  other  cases  the  feeling  arouses  activity  of 
the  glands,  which  stimulates  additional  organic  sensations 
and  these  keep  the  feelings  alive. 

Intensity  of  Feeling.  —  The  intensity  of  feeling  is  diflBcult 
to  measure.  We  do  not  discriminate  differences  of  intensity 
among  systemic  sensations  as  exactly  as  we  distinguish 
brightness  or  loudness.  It  is  difficult  to  get  at  the  stimuli  and 
experiment  on  their  changes. 

Some  attempts  have  been  made  to  measure  the  changes  of 
intensity  of  the  feeling  tone  which  accompanies  external 
sensations.  When  the  intensity  of  a  light  or  sound  or  pres- 
sure is  increased  continuously,  the  intensity  of  the  accom- 
panying feeling  varies  at  the  same  time.  But  this  change 
does  not  follow  Weber's  Law,  because  feelings  have  two 
opposite  phases,  pleasantness  and  unpleasantness,  while  per- 
ceptions have  only  one.  The  experiments  bring  out  the  fol- 
lowing relations: 

(1)  With  slight  intensity  of  stimulation  the  intensity  of  the 
accompanying  feeling  is  zero. 

(2)  As  the  intensity  of  the  stimulus  increases  there  is  at 
first  a  slight  degree  of  pleasantness. 

(3)  With  further  increase  in  the  intensity  of  stimula- 
tion the  pleasantness  increases  to  a  maximum  and  then  de- 
creases. 

(4)  At  a  certain  point  the  pleasantness  disappears  entirely^ 

(5)  With  further  increase  in  the  intensity  of  stimulation 
unpleasantness  appears  and  thereafter  increases  steadily. 

(6)  With  great  intensity  of  stimulation  a  maximum  degree 


208 


FEELING 


[CH.  IX 


of  unpleasantness  occurs;  this  marks  the  beginning  of  actual 
destruction  of  some  of  the  tissues.     [Fig.  70.] 

Importance  of  Feeling.  —  We  are  apt  to  underestimate  the 
importance  of  the  feelings  in  mental  life  because  they  are  so 

overshadowed  by  our  perceptions 
and  other  intellectual  experiences. 
The  knowledge  of  our  bodily  con- 
dition may  not  be  so  essential  to 
us  as  knowledge  of  the  outer 
world,  but  it  is  too  important  to 
be  ignored.  The  influence  of  feel- 
ing in  determining  a  man's  atti- 
tude toward  the  outer  world  is 
seen  if  we  compare  the  responses 
of  different  individuals  under  simi- 
lar conditions;  or  if  we  observe 
how  differently  the  same  person 
acts  in  two  cases  where  the  ex- 
ternal situation  is  similar  but  his 
own  internal  condition  is  radically 
different. 

Some  men  apparently  can  never  be  disheartened  or  in- 
sulted; others  will  collapse  at  the  slightest  misfortune,  or 
bristle  at  the  most  trivial  remark.  The  same  man  who  meets 
difficulties  energetically  and  cheerfully  when  he  is  in  good 
health,  may  refuse  to  face  danger  or  perplexity  when  affected 
by  indigestion,  malaria,  or  other  weakening  influences.  The 
external  stimuli  are  alike;  the  difference  lies  in  the  internal 
bodily  condition. 

We  can  only  appreciate  the  real  significance  of  feehng  in 
man's  mental  life  when  we  consider  its  influence  on  the  evolu- 
tion of  animal  species.  Destruction  of  tissue  is  harmful  to 
any  creature.  It  follows  that  any  species  or  creature  that 
develops  a  means  of  avoiding  the  destruction  of  its  tissues 
will  stand  a  better  chance  of  surviving.    Those  creatures  and 


Fig.  70.  —  Intensity  of 
Feeling 

The  curve  shows  how  the  feeling  ae- 
companying  a  ijerception  varies  with 
increase  of  stimulation.  Distance 
above  the  base-line  represents  degree 
of  pleasantness,  distance  below  repre- 
sents degree  of  unpleasantness;  hori- 
zontal distance  represents  intensity  of 
stimulation.  The  numbers  correspond 
to  the  six  laws  given  in  the  text. 


CH.  ix]  SIGNIFICANCE  OF  FEELING  209 

species  which  are  able  (1)  to  avoid  harmful  stimuli,  and  (2) 
to  react  positively  to  beneficial  stimuli,  are  most  likely  to 
survive  in  the  long  run.  These  two  opposite  types  of  response 
are  determined  by  the  two  opposite  phases  of  feeling.  So 
that  any  species  which  evolves  a  set  of  receptors  and  nerves 
for  feeling  has  gained  an  additional  and  important  means  of 
getting  along  in  life. 

Emotion 

Nature  of  Emotion.  —  Mental  life  is  especially  concerned 
with  the  interaction  between  the  body  and  the  outer  world. 
Accordingly,  the  most  important  development  of  feeling  is  in 
connection  with  the  motor  activities  which  it  arouses.  The 
most  significant  affective  experiences  are  not  pure  feelings, 
but  feelings  combined  with  powerful  motor  sensations. 
These  experiences  are  called  emotions. 

An  emotion  is  an  experience  made  up  of  both  systemic  and 
motor  sensations.  It  is  a  condition  of  mental  excitement, 
either  pleasurable  or  the  opposite  (usually  with  definite 
organic  or  pain  qualities),  accompanied  by  great  muscular 
activity  or  tension,  which  gives  rise  to  intense  muscle  sensa- 
tions. 

When  the  fire  alarm  is  sounded  your  heart  beats  faster  and 
your  legs  almost  irresistibly  carry  you  toward  the  scene. 
After  a  thunderbolt  your  heart  stops  beating  for  an  instant 
and  your  muscles  are  tense.  When  you  come  home  after  a 
long  absence,  you  feel  a  thrill  of  happiness  and  wave  your 
arms  or  shout  for  joy.  These  are  emotions;  they  consist  of 
systemic  and  motor  sensations  —  both  very  vivid. 

Emotion  is  the  only  secondary  experience  in  which  ideas  do 
not  play  a  prominent  part.  An  emotion  is  usually  aroused  by 
external  stimuli  or  by  ideas  which  represent  things  in  the 
external  world;  but  the  perception  or  idea  is  not  part  of  the 
emotion  —  it  fades  into  the  margin  when  the  emotion  surges 
into  prominence.     The  sight  of  the  smile  on  the  subway 


210  EMOTION  [cH.  IX 

guard's  face  as  he  slams  the  gate  on  you,  makes  you  boiling 
mad.  But  your  anger  is  the  bubbling  up  of  inner  feeling  and 
the  clenching  of  your  teeth  and  shaking  your  fist  —  not  the 
sight  of  the  guard.  The  anger  experience  is  composed  of 
sensations  stimulated  by  your  intense  physiological  and  mus- 
cular activity. 

According  to  popular  notions  the  essential  ingredient  of 
emotion  is  the  feeling  —  the  motor  display  is  an  after-effect. 
We  speak  of  "  emotion  and  its  expression."  This  interpreta- 
tion of  emotion  was  generally  accepted  by  psychologists  till 
about  thirty  years  ago.  It  assumes  that  we  first  experience 
the  feeling  of  anger,  then  clench  our  teeth  and  fists,  scowl,  and 
assume  the  general  anger  attitude. 

"William  James  and  Carl  Lange  independently  suggested 
that  the  factors  really  arise  in  the  opposite  order :  We  first  of 
all  assume  the  anger  attitude  —  clench  our  teeth  and  fists,  and 
strain  the  tension  of  our  muscles;  these  movements  in  turn 
stimulate  the  anger  feeling.  That  is,  according  to  these 
writers,  the  motor  sensations  generate  the  feeling  sensations 
which  compose  the  experience.  Many  psychologists  now 
accept  the  James-Lange  theory  of  emotion.  This  theory 
finds  some  confirmation  in  the  fact  that  if  we  artificially 
assume  the  anger  attitude  with  all  its  motor  accompaniments 
(for  instance,  when  we  act  a  part  in  a  play),  our  feelings  are 
aroused  very  strongly;  and  on  the  other  hand  when  we  are 
really  angry,  if  we  succeed  in  relaxing  our  muscles  and  so 
rid  ourselves  of  the  motor  sensations,  the  feeling  of  anger 
diminishes  and  the  entire  emotion  tends  to  disappear. 

However,  the  facts  seem  to  indicate  that  neither  of  the  two 
factors  has  precedence  in  emotion.  Both  systemic  and 
muscle  sensations  are  aroused  by  some  perception  or  thought; 
both  arise  together,  and  both  are  integral  parts  of  the  emo- 
tion. If  we  succeed  in  relaxing  the  muscles,  the  emotion 
vanishes  —  it  passes  over  into  a  simple  state  of  feeling.  If 
we  succeed  in  removing  the  systemic  sensations  the  emotion 


CH.  ix]  NATURE  OF  EMOTION  «11 

also  disapp>ears  —  it  is  reduced  to  a  simple  motor  experience 
called  conation  (ch.  xii).  Most  persons  are  able  to  control 
their  motor  expressions  more  readily  than  their  organic 
processes.  This  is  why  the  motor  factor  seems  to  be  the 
crucial  factor  when  we  test  emotions  experimentally.  We 
conclude,  then,  that  neither  the  popular  view  nor  the  James- 
Lange  theory  is  correct.  Emotion  is  the  joint  product  of 
nerve  impulses  from  the  systemic  and  motor  senses.  Emo- 
tional feeling  and  emotional  expression  are  equally  important 
parts  of  the  experience. 

The  glands  are  even  more  important  in  emotion  than  in 
feeling.  It  is  found  that  in  some  emotional  conditions  certain 
chemical  products,  such  as  adrenalin,  are  formed  in  great 
quantity  and  diffuse  themselves  among  the  neighboring 
organs.  These  compounds  are  apparently  the  stimuli  which 
arouse  the  systemic  elements  in  the  emotion.  Muscular  con- 
traction and  muscular  tension  serve  as  stimuli  for  the  motor 
elements. 

Primitive  Emotions.  —  Comparative  studies  on  animals 
indicate  that  emotion  is  present  in  many  s|>ecies  below  man. 
This  is  particularly  true  of  warm-blooded  animals,  including 
mammals  and  birds.^  Their  reactions  and  expressions  cor- 
respond so  closelj'  to  the  manifestations  of  human  emotion 
that  we  are  justified  in  attributing  real  emotional  experiences 
to  these  animals.  The  fundamental  kinds  of  emotion  may  be 
studied  to  advantage  in  subhuman  species,  where  they  are  not 
complicated  by  shadings  which  depend  on  thought  and  com- 
plex social  relations. 

In  popular  books  the  study  of  animal  emotion  consists  too 
often  in  attributing  to  pet  dogs  and  cats  various  shades  of 
human  emotion  which  depend  on  thought  and  reasoning. 
This  reading  of  human  experiences  into  lower  species  does 

*  In  cold-blooded  species  the  circulation  is  sluggish  and  there  b  not  that 
quickening  and  violent  agitation  which  is  characteristic  of  human  emotion. 
Their  emotions,  if  they  have  any,  are  essentially  different  from  ours. 


212  EMOTION  [ch.  ix 

not  help  us  to  understand  the  actual  facts.  The  mental 
processes  of  subhuman  species  are  far  simpler  than  in  man. 
The  emotional  display  in  the  dog  or  cat  is  not  the  result  of 
thought  —  it  occurs  without  thought  or  reasoning;  it  shows, 
rather,  to  what  extent  emotion  is  independent  of  thought  and 
more  primitive  than  thought.  What  will  help  us,  is  to  study 
carefully  the  manifestations  of  emotions  in  various  animal 
species  and  read  them  into  man.  When  a  cat  struts  away 
from  a  growling  dog  with  an  air  of  offended  dignity  she  has  a 
pride  emotion  of  some  sort,  but  no  thought  of  dignity.  The 
inciting  cause  of  the  emotion  is  a  perception,  not  an  idea. 
This  suggests  that  even  in  man  the  pride  emotion  depends 
perhaps  more  on  perceptions  and  less  on  ideas  than  is  gen- 
erally supposed. 

This  method  of  studying  emotion  is  helpful,  but  the  con- 
clusions should  not  be  carried  too  far.  Human  emotion 
differs  from  animal  emotion  in  the  prominent  part  which 
memories  and  thoughts  play  in  producing  it.  A  child  cries 
when  we  scowl  at  him,  or  exhibits  fear  at  the  sight  of  a  snake 
or  some  other  strange  creature.  His  emotion  is  aroused  by  a 
perception,  like  the  anger  of  the  bull  at  the  sight  of  red.  But 
in  the  human  adult,  emotions  are  determined  by  ideas  rather 
than  by  perceptions.  We  are  angry  when  we  see  a  big  boy 
beating  a  small  boy;  we  are  not  angry  when  we  see  a  strong 
man  beating  a  rug. 

The  most  primitive  emotions  in  man  are  those  based  on 
certain  fundamental  conditions  of  life,  which  led  to  the  evo- 
lution of  certain  types  of  reaction  in  animals  long  before  the 
human  species  appeared.  The  three  most  fundamental 
types  of  emotion  are  fear,  anger,  and  love. 

The  feeling  tone  of  fear  is  unpleasantness,  which  is  usually 
very  intense.  The  organic  sensations  which  form  part  of  the 
fear  exp>eriences  are  stimulated  through  receptors  in  the  lower 
viscera  and  in  the  region  of  the  lungs  and  heart.  The  char- 
acteristic motor  expressions  of  fear  are  certain  definite  mua- 


CH.  ix]  PRIMITIVE  EMOTIONS  218 

cular  contractions,  which  produce  trembling,  shrinking 
movements,  raising  of  the  eyebrows,  etc.  These  motor  ac- 
tivities furnish  muscle  sensations  which  form  an  important 
part  of  the  emotional  experience. 

In  anger  the  feeling  tone  is  also  unpleasant,  but  the  feeling 
tone  is  not  so  prominent  as  in  fear.  The  special  systemic 
sensations  are  derived  from  the  upper  digestive  tract,  the 
heart  and  lungs,  and  the  circulatory  system.  An  outburst 
of  anger  is  accompanied  by  vigorous  heart  activity  and 
breathing,  which  usually  causes  intense  flushing  of  the  face 
and  sometimes  a  choking  sensation  and  suffusion  of  the  eyes. 
The  characteristic  motor  activities  of  anger  are  clenching  of 
the  fists  and  teeth,  strained  tension  of  the  face  muscles,  and 
rigidity  of  the  lower  limbs.  These  motor  activities  are  accom- 
panied by  very  intense  muscle  sensations.  The  expression 
of  anger  is  generally  movement  toward  the  object  —  in  fear 
the  movement  is  away  from  its  object. 

Love  is  the  third  type  of  primitive  emotion.  Its  character- 
istic feeling  tone  is  pleasantness.  The  special  systemic  sen- 
sations are  less  prominent  than  in  fear  or  anger;  they  arise 
from  the  region  of  the  lungs  and  from  the  generative  organs. 
The  popular  notion  which  associates  the  emotion  of  love  with 
the  heart  is  not  so  far  wrong;  careful  observation  shows  that 
the  characteristic  sensation  is  located  somewhat  above  the 
heart,  but  that  it  is  due  to  the  circulation  and  not  to  breath- 
ing. There  are  various  motor  accompaniments  of  this  emo- 
tion, and  the  muscle  sensations  which  these  arouse  enter 
prominently  into  the  experience.  A  somewhat  less  intense 
variety  of  this  emotion  is  sympathy.  Here  the  general 
feeling  tone  (pleasantness)  is  most  prominent,  and  the  special 
systemic  sensations  are  less  definite  than  in  love.  The  motor 
expressions  of  sympathy  and  love  are  generally  movement 
toward  the  object.  In  sympathy  a  common  form  of  expres- 
sion is  activity  of  the  tear  glands. 

This  is  the  way  the  psychologist  describes  the  three  great 


214  EMOTION  [ch.  ix 

emotions  of  life.  It  sounds  very  different  from  the  descrip- 
tion of  the  poet  or  story-teller.  The  psychologist  and  the 
poet  have  something  quite  different  in  view.  The  poet  uses 
language  which  will  thrill  his  readers  and  arouse  the  same 
emotions  in  them.  The  psychologist  tries  to  show  what  sen- 
sations make  up  the  emotional  experience.  It  is  like  the 
attitude  of  the  cook  and  the  chemist  toward  the  soup.  The 
cook  wants  to  make  a  soup  that  will  tickle  the  palate;  the 
chemist  wants  to  know  what  is  in  the  soup.  Most  men  would 
prefer  to  see  love  through  the  poet's  eye  and  fear  or  anger 
through  the  psychologist's. 

Kinds  of  Emotion  in  Man.  —  Human  emotions  have  been 
classified  in  various  ways  according  as  one  characteristic  or 
another  is  selected  as  the  starting-point.  The  objection  to 
most  classifications  is  that  they  try  to  show  all  possible 
varieties  instead  of  those  that  are  really  significant.  Some 
types  of  emotion  have  developed  tremendously  and  show 
many  different  shades,  while  others  that  we  might  expect  to 
find  scarcely  appear  at  all.  We  can  only  discover  what  are 
the  really  important  emotions  in  human  life  by  actual  obser- 
vation and  experiment. 

An  important  aid  in  this  study  is  to  notice  the  various 
names  used  to  distinguish  emotions  in  the  languages  of 
civilized  and  uncivilized  races.  If  a  large  number  of  different 
names  for  a  certain  kind  of  emotion  are  found  in  a  given  lan- 
guage, we  infer  that  a  great  many  shades  of  that  emotion  are 
present  in  the  race  using  that  language. 

The  list  of  emotions  in  Table  VIII  is  based  on  the  different 
kinds  of  behavior  that  man  exhibits  with  reference  to  his 
surroundings.'  For  our  present  purpose  five  great  classes  of 
responses  may  be  distinguished:  nutritive,  reproductive, 
defensive,  aggressive,  and  social. 

Strictly  speaking,  the  nutritive  functions  do  not  lead  to 
emotions:  eating  and  its  various  accompaniments  are  usually 
^  See  ch.  x,  p.  237. 


CH.  DC 


TYPES  OF  HUMAN  EMOTION 


215 


Table  Vin.  —  Human  Emotions 


1.  Ex:pressiseXSidnt\ 

Ive) 

i.  Reproductive 

Emotion 

Expression 

Emotion 

Expression 

+Joy  (Enthusiasm) 

Diffused 

+Love 

Mating 

—Grief  (Despair) 

" 

+Lust 

<t 

—Shock 

«• 

—Jealousy 

t* 

+Mirth 

«« 

—Coyness 

"  (female) 

+Ecstasy 

« 

+Tenderness 

Maternal 

Restiveness 

«4 

Exuberance 

Play 

+Wonder 

Curiosity 

3.  Defensive 

4.  Aggressive 

-Fear 

Flight  and  Hiding 

-Anger  (Rage)  Fighting 

—Disgust 

Avoiding 

-Hatred 

Resenting 

—Timidity 

Shyness 

-Envy 

Rivalry 

(Embarrassment) 

+Pride 

Domineering 

—Shame 

Covering 

+Exultation 

" 

+Awe 

Submission 

5.  Soeixd 

6.  With  Temporal  Projection 

+ Affect  ion 

Family  relations 

Retrospective 

Reference: 

+Cordiality 

Herding 

-Regret  (Remorse) 

-Pity 

Sympathetic 

+Satisfaction  (Elation) 

+Gratitude 

M 

Surprise 

+Admiration 

^ 

Prospective  Reference: 

—Detestation 

Antipathetic 

+Hope 

-Revenge 

•t 

-Dread 

—Suspicion 

•I 

Anxiety 

-Scorn 

unemotional  acts.  But  there  are  certain  expressive  emotions 
of  an  indefinite  or  difiPused  sort  which  depend  indirectly  on 
the  nutritive  life.  Joy,  grief,  and  the  like  are  expressive 
emotions,  made  up  of  diffused  feelings. 

The  defensive,  aggressive,  and  reproductive  emotions  are 
represented  by  the  emotions  of  fear,  anger,  and  love,  which  we 
have  already  examined.  These  are  the  original  forms;  the 
table  shows  a  number  of  other  well-known  emotions  that  have 
developed  out  of  them. 


216  EMOTION  [ch.  ix 

The  social  life  of  man  in  relation  to  his  fellows  develops 
special  emotions.  Some  social  emotions  are  defensive  or 
aggressive,  but  others  do  not  belong  in  either  of  these  groups. 
The  fifth  class  in  the  table  includes  the  social  emotions  that 
are  not  connected  with  other  sorts  of  behavior. 

There  are  also  emotions  that  are  essentially  connected  with 
ideas  of  the  past  or  the  future.  The  prospective  emotion  of 
hope,  and  the  retrospective  emotion  of  satisfaction  are  similar 
to  joy  apart  from  the  time  reference. 

In  the  table  the  kind  of  feeling  tone  that  is  characteristic 
of  each  emotion  is  shown  at  the  left  and  the  kind  of  motor 
expression  at  the  right.  In  most  emotions  the  feeling  tone  is 
definitely  pleasant  (-i-)  or  unpleasant  (  — ).  Certain  sorts, 
such  as  restiveness  and  surprise,  may  be  either  pleasant  or 
unpleasant.  Frequently  they  alternate  between  one  quaUty 
and  the  other. 

In  many  cases  we  may  readily  notice  several  different 
shades  of  emotion  under  the  same  general  type.  It  is  easy  to 
distinguish,  for  example,  between  anger  and  rage.  Some  of 
these  varieties  are  of  considerable  importance  in  mental  life; 
remorse,  for  example,  has  very  different  consequences  from 
regret.  Some  of  the  less  important  distinctions  are  interest- 
ing to  study.  Notice  the  difference  between  '  feeling 
slighted,'  'pique,'  'feeling  insulted,'  'feeling  outraged'; 
or  between  various  degrees  of  mirth. 

Adapting  Emotions  to  Civilized  Life.  —  The  emotional  life 
has  not  kept  pace  with  the  other  phases  of  mental  evolution. 
Perception,  memory,  and  other  types  of  experience  have 
adapted  themselves  to  changing  conditions,  but  our  emo-^ 
tional  experiences  continue  in  almost  primitive  form.  Many 
of  the  more  important  emotions  seem  like  echoes  of  our 
prehuman  ancestors;  they  do  not  fit  into  the  social  life  of 
to-day. 

The  emotion  of  anger  is  well  adapted  to  the  food-getting 
activities  of  carnivorous  animals.    It  stimulates  them  to 


,\ 


CH.  ix]  TRAINING  THE  EMOTIONS  217 

greater  exertions  and  seems  really  to  help  them  in  overcoming 
their  prey.  Even  in  primitive  man  strength  is  more  impor- 
tant than  skill.  But  under  modern  conditions  of  civilized  life 
intellectual  adjustment  and  motor  coordination  are  far  more 
valuable  than  mere  strength.  A  Foch  or  a  Hindenburg  is 
the  brains  of  the  army,  not  its  fist.  The  man  who  gives  way 
to  blind  rage  in  the  presence  of  an  adversary  is  usually  at  a 
disadvantage.  We  look  upon  unbridled  emotion  of  any  sort 
as  childish  or  brutish;  one  who  has  not  learned  to  control 
the  display  of  emotion  is  held  more  or  less  in  contempt. 
People  are  even  apt  to  regard  the  shell-shocked  veteran  as  a 
coward,  though  really  his  disability  should  arouse  the  same 
feeling  as  the  loss  of  a  leg  in  battle. 

Since  our  emotional  inheritance  is  unsuitable  to  present 
conditions,  the  obvious  course  is  to  direct  this  phase  of  mental 
life  into  more  suitable  paths  by  systematic  training.  This  is 
one  of  the  most  important  tasks  of  education,  socially  speak- 
ing. Emotional  training  is  not  so  prominent  a  feature  of 
our  present-day  educational  systems  as  intellectual  training; 
it  is  generally  accomplished  indirectly  or  incidentally. 
School  discipline  and  home  discipline,  especially  through 
punishment  and  admonition,  teach  the  child  to  repress  or 
suppress  violent  displays  of  emotion.  Social  tradition  and 
example  help  considerably.  The  child  finds  that  he  makes 
himself  ridiculous  by  giving  free  vent  to  his  emotions.  The 
*  cry-baby  '  is  an  object  of  contempt  among  children;  the 
stolid  child  or  youth  is  admired  by  his  playmates. 

The  ideal  of  a  calm,  passionless  life  may  perhaps  be  socially 
desirable,  but  it  does  not  take  into  account  the  innate  pro- 
pensities of  the  individual.  No  boiler  is  strong  enough  to 
resist  every  pressure,  and  the  engineer  who  clamps  down  the 
safety-valve  is  heedless  of  the  best  interests  of  his  machine. 
Expression  isj:he  safety-valve  of  emotion^  The  emotional 
tendencies  are  part  of  our  mental  inheritance.  It  is  not 
possible  to  eradicate  them  entirely.     Freud  has  shown  that 


Jx4^-«^ 


->-«^^0<^^ 


218  EMOTION  [ch.  ix 

the  struggle  to  suppress  them  often  results  in  nervous  dis- 
organization. On  the  moral  side  it  fosters  deceit  and 
hypocrisy.  A  rational  training  of  the  emotions  would  con- 
sist in  modifying  their  feeling  elements  and  directing  their 
motor  expression  into  useful  channels. 

The  various  classes  of  emotions  differ  considerably  in 
value.  The  defensive  emotions  refer  back  to  prehistoric 
modes  of  defense,  and  for  the  most  part  hamper  us  under 
modern  conditions.  The  same  is  true  of  the  aggressive  emo- 
tions. On  the  other  hand,  the  social  emotions  harmonize 
well  with  modern  social  conditions,  excepting  those  which 
are  distinctly  antipathetic.  The  reproductive  emotions 
(especially  love  and  tenderness)  are  by  no  means  anachro- 
nistic, but  they  require  careful  training  to  fit  them  into  the 
social  life  of  civilized  man.  In  some  communities  this  train- 
ing has  gone  to  extreme  lengths. 

The  expressive  emotions  and  the  retrospective  and  pro- 
spective types  are  socially  neutral.  Extreme  manifestations 
of  joy,  grief,  mirth,  regret,  hope,  and  the  like,  do  not  fit  in 
with  modern  life;  but  a  moderate  display  of  these  emotions 
is  not  socially  detrimental  and  is  of  some  benefit  to  the  bio- 
logical life  of  the  individual. 

In  short,  psychology  and  pedagogy  should  recognize  that 
the  emotional  side  of  our  mental  life  is  to  some  extent  behind 
the  times.  Uncontrolled  emotion  hampers  the  proper  inter- 
action between  the  individual  of  to-day  and  his  environment. 
It  is  only  when  our  primitive,  inherited  emotions  are  trained 
into  socially  acceptable  modes  of  expression  that  this  phase 
of  mental  life  is  brought  into  harmony  with  the  rest  of  our 
experiences  and  actions. 

Sentiment  \ 

Nature  of  Sentiment.  —  Besides  feeling  and  emotioivthere 
is  another,  less  important  experience  connected  with  our 
inner  bodily  processes,  called  sentiment.      A  sentiment  is 


CH.  ix]  NATURE  OF  SENTIMENT  219 

an  experience  which  is  made  up  of  systemic  sensations  and 
ideas.  ^ 

Sentiments  may  be  aroused  by  any  external  sensation  or 
idea,  but  the  experience  itself  is  essentially  difiFerent  from 
either.  Your  "  sense  of  beauty  "  is  not  a  sensation  nor  a 
perception,  but  a  sentiment.  It  may  be  aroused  by  seeing 
the  Venus  de  Milo,  or  by  listening  to  Beethoven's  Fifth 
Symphony,  or  by  the  memory  of  one  of  these  experiences; 
but  the  sentiment  of  beauty  is  not  the  perception  of  the 
object.  The  perception  suggests  the  sentiment,  and  then 
fades  into  the  background  of  the  new  experience.  The  promi- 
nent elements  in  the  sentiment  of  beauty  are  a  feeling  and 
an  idea  of  value  (ch.  xiii). 

When  something  has  aroused  a  sentiment,  and  the  same 
situation  continues  to  affect  us,  we  connect  the  sentiment 
with  the  perception  and  read  it  into  the  objective  situation. 
The  statue  '  looks  beautiful.'  The  world  about  us  '  looks 
real.*  A  locomotive  appears  powerful.  An  action  appears 
good. 

Are  the  beauty,  reality,  and  power  in  the  objects  them- 
selves? Is  the  *  goodness  '  in  the  action  or  in  the  actor?  In 
discussing  feeling  we  noticed  that  pain  is  not  a  quality  of  the 
sharp  knife,  though  we  experience  pain  when  the  knife  cuts 
us,  and  the  pain  is  stimulated  by  the  sharp  edge.  In  much 
the  same  way  the  sentiment  of  beauty  is  stimulated  by  cer- 
tain combinations  of  tones  in  music  or  by  certain  curves  or 
color  combinations  in  a  painting;  but  it  is  not  a  quality  of  the 
music  or  painting.  And  the  same  is  true  of  power  and  good- 
ness. Our  sentiments  are  generated  within  us;  they  are 
intimately  personal,  like  pain,  and  yet  they  are  excited  by 
something  in  the  external  stimulus. 

'  The  term  sentiment  has  a  special  meaning  in  psychology.  It  is  not  pre- 
cisely what  we  mean  by  *a  sentiment*  in  ordinary  language,  and  it  does 
not  correspond  to  the  adjective  'sentimental';  but  it  carries  a  trace  of  each 
notion  —  the  imagery  of  'a  sentiment'  and  the  feeling  tone  of  'sentimental.' 


220  SENTIMENT  [ch.  ix 

Kinds  of  Sentiments.  —  Sentiments  are  classified  according 
to  the  kind  of  experience  that  arouses  them.     [Table  IX.] 

Table  IX. —  Classification  of  Sentiments 
Sentiments  Source 

Reality  Feelings Perceptions 

Beliefs Ideas 

Esthetic  Sentiments Systemic  Experiences 

Dynamic  Sentiments Motor  Experiences 

Moral  Sentiments Social  Situations 

The  sentiment  of  realness,  or  reality  feeling,  attaches  to  per- 
ceptions of  the  outer  world.  We  are  sure  that  the  objects 
which  we  see,  palp,  heft,  hear,  etc.,  really  exist.  Usually  this 
sureness  or  conviction  is  marginal.  Like  the  familiarity  feel- 
ing, it  is  only  a  subordinate  element  in  the  perception.  In 
adult  life  the  reality  feeling  rarely  occurs  as  an  independent 
experience.  It  takes  something  unexpected,  or  something 
that  does  not  fit  in  with  our  general  scheme  of  things  to  bring 
it  out  vividly.  If  we  meet  a  friend  who  was  supposed  to  be 
a  thousand  miles  away,  the  reality  of  his  presence  bursts 
through  into  prominence.  The  other  extreme  occurs  in  day- 
dreaming, or  when  we  are  dazed  by  a  sudden  blow  or  a  loud 
noise:  then  the  reality  element  is  quite  lacking  —  things  about 
us  do  not  impress  us  as  real.  In  certain  pathological  condi- 
tions the  sense  of  reality  disappears  completely:  the  patient 
declares  that  the  world  does  not  seem  real. 

Belief  is  very  much  like  reality  feeling,  except  that  it  is 
associated  with  ideas.  We  are  sure  that  certain  of  our  images 
and  thoughts  are  true.  Two  opposite  varieties  of  belief  have 
developed :  aflSrmative  belief,  and  negative  belief  or  disbelief. 
We  may  either  believe  in  the  existence  of  the  object  we  are 
thinking  of;  or  we  may  believe  that  no  such  object  exists. 
When  you  picture  a  mermaid,  your  sentiment  is  belief  in  its 
falsity,  while  if  you  have  a  mental  picture  of  Vesuvius  the 
sentiment  takes  the  form  of  belief  that  this  volcano  actually 
exists.    In  the  two  cases  the  sentiment  is  of  the  same  type  — 


CH.  IX]  TYPES  OF  SENTIMENT  221 

belief  —  but  our  attitude  is  different  (ch.  xv).  The  'not' 
attitude  gives  a  sjjecial  tinge  to  the  sentiment.  The  true 
opposite  of  belief  is  not  disbelief,  but  doubt.  Doubt  is  a 
sentiment  which  arises  from  alternation  of  belief  and  dis- 
belief. 

Esthetic  sentiments  arise  when  the  feeling  tone  of  an  experi- 
ence is  especially  intense  and  combines  with  an  idea  of  value. 
This  produces  a  sentiment  of  beauty  or  harmony  if  the  feeling 
is  pleasant,  and  a  sentiment  of  ugliness  or  discord  if  the  feeling 
is  unpleasant.  The  intensity  of  the  esthetic  sentiments 
varies  considerably  with  the  individual  and  with  training. 
In  some  persons  an  appreciation  of  beauty  and  harmony 
appears  early  in  life  and  develops  without  any  special  train- 
ing; in  others  it  is  only  attained  gradually,  through  education 
and  imitation.  Esthetic  sentiments  are  especially  character- 
istic of  the  '  artistic  '  type  of  personality. 

Dynamic  sentiments  arise  when  vivid  motor  sensations  are 
associated  with  our  perceptions.  These  motor  sensations  are 
stimulated  by  the  activity  of  our  own  muscles;  but  their 
intensity  depends  upon  the  weight  or  resistance  of  objects 
that  we  try  to  move.  In  connection  with  our  voluntary 
movements  there  is  a  sense  of  power  or  abUily  to  act.  If  the 
resistance  is  strong,  we  have  a  sense  of  opposition,  of  being 
thwarted,  of  force  or  power  in  the  environment.  These  are 
dynamic  sentiments.  A  tornado,  a  great  factory  machine  in 
action,  arouse  a  sentiment  of  the  power  of  inanimate  nature. 
The  religious  sentiment  is  due  to  an  idea  of  some  mighty 
power  in  the  universe.  Dynamic  and  esthetic  sentiments 
combine  to  form  the  sentiment  of  the  sublime. 

Moral  sentiments  come  from  feelings  which  attach  to  our 
perceptions  of  social  acts  —  usually  the  actions  of  other  per- 
sons. The  *  traflSc  cop  '  who  goes  over  and  leads  a  blind  man 
across  the  street  arouses  your  approval;  the  youngster  who 
hurls  a  stone  through  a  shop  window  arouses  a  feeUng  of  dis- 
approval.    In  each  instance  the  feeling  combined  with  the 


222  SENTIMENT  [ch.  ix 

idea  of  social  value  forms  a  moral  sentiment, —  in  one  case  a 
sentiment  of  right,  in  the  other  a  sentiment  of  wrong. 

Sentiments  are  the  least  important  kind  of  experience.  If 
a  sentiment  is  weak  it  becomes  an  element  in  some  other  state 
of  mind.  If  it  grows  intense,  it  tends  to  bring  about  some 
motor  expression;  this  arouses  muscle  sensations  and  the 
experience  is  no  longer  a  mere  sentiment.  Esthetic  senti- 
ments pass  readily  into  emotions;  dynamic  sentiments  arouse 
an  impulse  to  overcome  resistance  or  to  exert  our  own  power. 
Moral  sentiments,  if  they  are  vivid,  are  likely  to  pass  over 
into  voluntary  actions.  We  are  not  content  with  merely  con- 
demning or  approving  the  actions  of  others.  If  a  wrong 
appeals  to  us  deeply,  we  are  apt  to  start  in  to  remedy  it.  We 
'  push  along  '  a  good  thing  —  literally  as  well  as  figuratively. 

In  a  word,  sentiments  lack  stable  equilibrium;  if  they  are 
weak  they  are  crowded  out  of  focus  by  other  experiences;  if 
they  are  intense  this  very  strength  transforms  them  into 
something  else.  Beliefs  are  the  most  stable  of  all  sentiments. 
Our  belief  in  the  multiplication  table  and  other  fundamental 
truths  persists  unaltered  throughout  life.  Other  underlying 
beliefs  undergo  certain  changes  from  time  to  time,  but  still 
remain  as  enduring  sentiments. 

Summary.  —  In  this  chapter  we  have  examined  three  sorts 
of  experience  in  which  systemic  sensations  are  prominent. 
Feelings  are  experiences  consisting  almost  wholly  of  (1) 
organic  sensations  —  that  is,  sensations  from  the  internal 
organs  of  digestion,  reproduction,  circulation,  respiration, 
and  other  bodily  processes,  —  or  (2)  pain  sensations,  or  (3) 
feeling  tone  and  general  sensibility.  Feelings  are  experiences 
of  our  own  bodily  condition,  and  may  be  contrasted  with 
perceptions,  which  are  experiences  of  the  outer  world. 

Emotions  are  experiences  in  which  both  systemic  and  motor 
sensations  are  prominent.  They  combine  feeling  and  action. 
In  general  they  are  more  intense  and  vivid  than  simple  feel- 
ings and  occupy  a  specially  prominent  place  in  mental  life. 


CH.  ix]  SUMMARY  223 

Emotional  experiences  belong  to  primitive  conditions  of  life 
and  do  not  fit  in  especially  well  with  man's  higher  mental 
evolution. 

Sentiments  are  experiences  which  combine  systemic  sensa- 
tions with  ideas.  They  are  generally  weak  and  unimportant 
in  mental  life.  Belief  is  the  most  hardy  of  all  the  sentiments. 
The  others  tend  to  fade  into  the  background,  or  they  lead  to 
action  and  so  are  transformed  into  some  other  kind  of 
experience. 

Practical  Exercises: 

44.  Analyze  your  general  state  of  feeling  at  three  different  times;  e.g.  on 
waking,  after  a  hearty  meal,  after  a  brisk  walk. 

45.  Describe  the  expression  of  three  different  emotions,  in  cases  you 
have  witnessed  recently. 

46.  Analyze  some  powerful  emotion  of  your  own  at  the  time  or  soon  after 
the  outburst  has  subsided. 

47.  Mention  some  fact  which  you  believe  thoroughly;  also  some  statement 
which  you  are  sure  is  false;  also  something  about  which  you  are  in  real 
doubt.  Now  examine  the  sentiment  you  have  in  each  case  —  the 
belief,  the  disbelief,  and  the  doubt;  describe  them  as  far  as  possible. 

48.  Describe  the  expression  of  anger  (or  fear)  in  a  child. 

References: 
On  feeling:  E.  B.  Titchener,  Psychology  of  Feeling  and  Attention,  chs.  2-4. 
On  classes  of  emotion:  W.  McDougall,  Social  Pirychology,  chs.  .S-6. 
On   theory   of  emotion:   W.   James,    Principles  of  Psychology,   ch.  25; 

C.  Darwin,  Expression  of  the  Emotions  in  Man  and  Animals. 
On  the  physiology  of  emotions:  C.  W.  Crile,  Origin  and  Nature  of  the  Emo- 
turns;  W.  B.  Cannon,  Bodily  Changes  in  Pain,  Hunger,  Fear  and  Rage. 


CHAPTER  X 
INSTINCT 

Motor  Experiences  and  Response.  —  The  experiences  so 
far  examined  belong  to  two  separate  groups:  (1)  Perceptions, 
memories,  and  their  kindred  are  based  on  the  information  we 
receive  from  the  outer  world.  (2)  Feelings  and  emotions  are 
concerned  with  internal  conditions  and  are  stimulated  by  the 
physiological  processes  which  go  on  within  our  own  body. 
There  is  still  a  third  class  called  motor  experiences,  which  are 
composed  largely  of  motor  sensations.  The  muscle  sense  and 
static  sense  furnish  information  about  our  movements  and 
responses,  and  about  our  bodily  postures  with  reference  to  the 
outer  world.  These  sensations  are  organized  into  experiences 
called  conations,  and  when  joined  to  images  and  thoughts 
they  develop  into  secondary  experiences  called  volitions  and 
language. 

Motor  experiences  differ  from  other  experiences  in  one 
important  respect:  We  perceive,  we  imagine,  we  feel,  before  we 
act.  Motor  experiences,  on  the  other  hand,  are  the  result  of 
our  motor  activity;  they  arise  after  the  motor  nerve  impulses 
have  begun  to  affect  our  muscles.  When  we  walk,  we  sense 
each  movement  of  our  limbs  as  it  takes  place.  In  other 
words,  whereas  perceptions,  images,  and  feelings  keep  us  in 
touch  with  the  stimuli  that  affect  us,  conations  and  other 
motor  experiences  are  concerned  chiefly  with  our  responses. 
Before  taking  up  these  motor  experiences,'  we  must  examine 
the  motor  side  of  the  nervous  operation  and  see  how  it  is 
related  to  stimulation. 

Every  stimulus  starts  an  impulse  in  the  sensory  nerves, 
which  proceeds  to  some  center  in  the  spinal  cord  or  brain. 
^  See  chs.  xii,  xiii. 


CH.  x]         EXPERIENCE  AND  RESPONSE  225 

In  these  central  neurons  there  is  a  certain  amount  of  latent 
nerve  energy,  so  that  the  incoming  impulses,  instead  of  being 
*  absorbed,'  actually  arouse  a  greater  amount  of  nervous  activity 
at  the  centers,  and  this  activity  seeks  an  outlet  into  other 
neurons.  The  nervous  activity  aroused  in  the  brain  by  visual 
stimuli  results  first  in  our  perceiving  the  scenes  around  us, 
and  this  perception  may  be  followed  by  a  series  of  memories 
and  fancies.  But  this  succession  of  events  in  the  brain  does 
not  continue  indefinitely.  In  the  end  the  central  impulse 
finds  an  outlet  into  some  motor  path  and  passes  out  of  the 
brain  and  down  to  some  muscle,  where  its  energy  is  expended 
in  producing  muscular  contraction.  The  final  result  of  the 
nerve  impulse  in  this  case  is  movement.  In  other  cases  the 
outlet  is  into  a  path  leading  to  some  gland,  and  the  final  result 
is  the  chemical  process  of  secretion.  Our  notion  of  nervous 
activity  will  be  incomplete,  then,  if  we  stop  at  the  central 
processes  of  perception,  feeling,  and  the  like.  Every  stimulus 
tends  in  the  end  to  bring  about  some  response.  The  most  signif- 
icant feature  of  the  entire  nervous  and  mental  process  is  not 
the  information  it  furnishes,  but  the  way  we  act  upon  this 
information.  Action  by  a  creature  in  response  to  stimula- 
tion is  called  behavior. 

Kinds  of  Behavior.  —  Behavior  may  be  grouped  into  the 
following  classes: 

Diffused  movements 
Reflexes 

Autonomic  functions 
Instinctive  behavior 
Intelligent  behavior 

(1)  Diffused  Movements:  Nerve  impulses  always  follow 
the  path  of  least  resistance.  If  the  neurons  were  not  arranged 
in  definite  groups  and  chains,  the  nerve  impulses  might  follow 
all  sorts  of  paths  and  our  responses  would  be  largely  a  matter 
of  chance.  The  same  stimulus  would  lead  now  to  this  move- 
ment, now  to  that,  at  random,  without  any  appropriateness 


226  BEHAVIOR  [ch.  x 

whatever.   Impulses  would  tend  to  spread  into  several  chan- 
nels at  once  and  cause  diffused  movements. 

Diffused  movements  occur  in  the  new-born  child.  \Mien 
he  is  affected  at  the  same  time  by  several  stimuli  none  of 
which  is  especially  intense,  his  responses  are  uncoordinated; 
they  bear  no  significant  relation  to  the  stimuli.  Observe  a 
child  lying  on  his  back  when  nothing  in  particular  is  affecting 
him.  He  wriggles  his  arms,  gurgles,  winks,  kicks  about, 
moves  his  toes,  his  lips,  his  eyes,  his  head.  These  diffused 
random  movements  are  the  result  of  general  stimulation  by 
light,  pressure,  warmth,  and  sounds.  The  incoming  impulses 
are  weak  and  diffused;  they  find  outlets  here  and  there 
through  various  motor  channels. 

(2)  Reflexes:  Diffused  response  is  not  the  only  form  of 
behavior  in  the  new-born  child.  Our  nervous  system  is 
arranged  at  the  start  by  heredity  in  an  orderly  way.  The 
sensory  and  motor  centers  are  placed  in  very  definite  rela- 
tions to  one  another.  From  the  very  beginning  certain  sen- 
sory paths  are  closely  connected  with  certain  motor  paths,  so 
that  stimuli  which  affect  a  given  receptor  are  bound  to  bring 
about  certain  definite  responses.  If  an  infant's  palm  is 
touched  with  a  stick  he  grasps  it;  if  a  milk  bottle  is  put  to  his 
mouth  his  lips  close  around  it;  certain  stimuli  produce 
coughing,  others  produce  sneezing.  These  are  immediate 
responses,  brought  about  by  inherited  connections  between 
sensory  and  motor  nerve  paths.  A  definite  response  to  a 
definite  stimulus,  due  to  an  inherited  arrangement  of  the 
nerve  paths,  is  called  a  reflex,  or  reflex  action. 

(3)  Autonomic  Functions:  The  earliest  reflexes  that  occur 
in  a  child's  life  are  due  to  systemic  stimuli.  Long  before  birth 
the  heart  begins  to  beat  through  stimuli  which  arouse  activity 
of  the  heart  muscles.  Immediately  after  birth  the  lungs  are 
stimulated  and  the  result  is  muscular  activity  which  draws  the 
air  into  the  lungs  and  expels  it  again.  These  responses, 
which  control  the  bodily  processes  of  circulation  and  respira- 


CH.  x]  KINDS  OF  BEHAVIOR  227 

tion,  are  so  arranged  that  each  response  furnishes  a  stimulus 
for  another  reflex  of  the  same  sort.  They  form  a  chain  of 
reflexes,  which  continue  in  endless  series  during  the  entire  life 
of  the  individual.  Regardless  of  the  environment  (except 
in  a  general  way),  the  lungs  expand  and  contract,  the  heart 
pumps  blood  into  the  arteries  continuously  till  death. 

These  chains  of  reflexes  which  govern  the  life  processes  are 
called  autonomic  functions.  They  are  of  the  utmost  impor- 
tance to  life;  but  since  they  are  only  indirectly  concerned  with 
the  individual's  relations  to  his  environment,  they  do  not 
interest  psychologists  especially.  Their  special  bearing  on 
psychology  lies  in  the  fact  that  the  autonomic  nervous  system 
is  connected  with  the  main  cerebrospinal  nervous  system 
(ch.  ii).  By  reason  of  this  connection  the  autonomic  func- 
tions may  be  modified  by  motor  impulses  from  the  brain  and 
spinal  centers.  This  occurs,  for  example,  in  voluntary 
changes  of  respiration  and  in  the  changes  in  heart  activity 
that  accompany  the  emotions. 

The  digestive  processes  are  controlled  by  the  autonomic 
system  also.  But  they  do  not  form  a  single  continuous  series 
of  reflexes  like  respiration  and  circulation.  Digestion  de- 
pends upon  stimulation  by  food  in  the  stomach  or  intestines; 
in  the  absence  of  food  the  digestive  organs  are  comparatively 
inactive.  When  food  is  taken  into  the  mouth  the  digestive 
organs  are  stimulated  and  the  autonomic  processes  begin  to 
act  at  once;  they  include  a  whole  series  of  digestive  activities 
ending  in  the  excretion  of  the  waste  products.  All  these 
processes  are  subject  to  some  control  by  the  cerebrospinal 
system,  and  often  serve  to  stimulate  and  modify  its  activities. 
Apart  from  this  connection,  psychology  is  not  particularly 
concerned  with  the  autonomic  functions. 

(4-)  Instinctive  Behavior:  The  nervous  connections 
within  the  cerebrospinal  system  are  not  so  close  as  those  of 
the  autonomic  nerves.  There  is  more  branching  of  neurons 
and  consequently  more  possibility  of  alternative  motor  dis- 


228  BEHAVIOR  [ch.  x 

charges.  But  the  various  nerve  paths  and  centers  are  so 
arranged  by  inheritance  that  certain  connections  are  inevi- 
table, especially  in  early  life.  Not  only  are  there  from  the 
beginning  certain  definite  reflexes  to  external  stimulation,  but 
some  of  these  reflexes  cause  stimuli  which  produce  other 
reflexes,  so  that  when  a  given  stimulus  occurs  a  definite  chain 
of  reflexes  inevitably  follows.  This  is  best  illustrated  in  the 
feeding  activity  of  the  infant.  The  contact  of  the  lips  with 
the  breast  or  bottle  causes  the  lip-grasping  reflex.  This 
serves  as  stimulus  to  the  sucking  reflex.  The  milk  in  turn 
stimulates  the  swallowing  reflex.  Any  succession  of  cerebro- 
spinal reflexes  like  this,  in  which  one  response  provides  the 
stimulus  for  the  next,  is  called  an  instinct,  or  instinctive 
behavior. 

In  subhuman  species,  where  the  branching  connections  are 
not  so  numerous  as  in  man,  a  large  part  of  behavior  is  of  the 
instinctive  type.  Remember  that  in  any  instinctive  act  the 
successive  steps  follow  in  natural  order  —  each  is  caused  by 
the  preceding.  There  is  no  delay;  no  thinking  and  deciding 
what  to  do.  The  progress  of  the  action  is  automatic  ^  unless 
checked  by  some  interfering  stimulus.  Instinctive  behavior 
generally  brings  about  some  result  that  is  useful  to  the  crea- 
ture ;  that  is,  it  is  adaptive.  This  is  because  the  nervous  struo 
ture,  like  the  rest  of  the  body,  has  grown  up  in  the  course  of 
long  ages  of  time  through  the  natural  selection  of  useful 
arrangements  of  the  neurons  and  centers. 

(5)  Intelligent  Behavior:  The  branching  connections  in 
the  nervous  system  make  possible  still  another  type  of  behav- 
ior. Reflexes  that  are  not  so  closely  connected  as  to  form 
instincts,  may  come  in  time  to  be  grouped  into  hard  and  fast 
series  of  actions  which  are  of  the  utmost  importance  to  life. 
A  series  of  useful  movements  whose  connection  is  not  based 
on  heredity,  but  is  acquired  by  the  individual,  is  called  intelli- 
gent behavior.  If  the  act  becomes  so  fixed  that  it  proceeds  as 
^  Not  to  be  confused  with  autonomic. 


CH.  x]  KINDS  OF  BEHAVIOR  229 

automatically  as  an  instinct,  it  is  called  a  habit.     Speaking 
and  writing  are  instances  of  human  habits. 

The  human  adult  finds  it  difficult  to  draw  a  sharp  line 
between  instinctive  and  intelligent  behavior  in  the  case  of  his 
own  actions.  Early  in  life  our  instincts  begin  to  be  modified, 
and  these  new  modes  of  action  are  often  so  quick  and  auto- 
matic that  they  seem  to  be  inborn.  Most  of  our  actions  have 
marked  instinctive  elements  and  equally  marked  intelligent 
elements.  Walking  is  especially  hard  to  classify.  When  the 
child  starts  to  walk  his  movements  are  uncertain,  and  they 
seem  to  improve  by  practice;  but  the  fact  that  walking  always 
develops  at  about  the  same  age  indicates  that  it  depends 
fundamentally  on  certain  inherited  factors.  On  the  whole  the 
act  of  walking  seems  to  be  mainly  instinctive  in  man. 

Reflex  Behavior 

Nature  of  the  Reflex.  —  The  reflex  is  the  simplest  form  of 
response  in  creatures  possessing  a  nervous  system.  It  in- 
volves the  operation  of  a  single  nervous  arc  or  a  number  of 
arcs  acting  together. 

The  characteristic  feature  of  reflex  activity  is  that  the 
response  is  definite,  not  diffuse.  This  makes  it  a  suitable  type 
of  activity  for  response.  It  accomplishes  something.  The 
infant's  diffuse  movements  are  responses  to  stimulation,  but 
they  are  not  especially  adaptive  —  they  do  not  answer  the 
problems  which  the  stimuli  set  before  the  child.  Definite 
reactions  of  the  reflex  type  do  this.  Winking  protects  the 
eyes;  swallowing  assists  the  nourishment  process.  Even 
glandular  reflexes  may  solve  some  of  the  minor  problems  of 
life,  —  weeping  may  remove  a  cinder  from  the  eye. 

While  reflex  activity  is  definite,  it  is  by  no  means  invariable: 
the  response  usually  varies  with  the  intensity  of  the  stimulus. 
Very  intense  stimulation  generally  causes  violent  muscular 
contraction,  and  the  effect  is  apt  to  be  widespread.  The 
shudder  reflex  extends  over  a  larger  part  of  the  body  when  the 


230  REFLEX  BEHAVIOR  [ch.  x 

stimulus  is  more  intense.  The  tickle  reflex  is  an  exception  to 
this  rule:  the  tickle  stimulus  is  less  intense  than  the  ordinary 
touch  stimulation,  but  its  peculiar  quality  brings  about  a 
much  more  violent  response  than  ordinary  contact. 

Varieties  of  Reflex  Action.  —  In  reflex  action  the  stimulus 
starts  a  nerve  impulse  along  the  sensory  nerve  toward  the 
central  part  of  the  nervous  system;  at  the  center  the  impulse 
passes  over  to  a  motor  path  and  descends  to  a  muscle  or 
gland,  causing  responsive  activity.  This  process  may  be 
complicated  in  two  ways:  (1)  The  impulse  may  either  cross  to 
the  motor  path  and  pass  out  at  the  first  opportunity;  or  it 
may  proceed  to  a  higher  center  and  then  pass  out.  On  this 
basis  reflexes  are  divided  into  lower  and  higher.  (2)  The 
sensory  impulse  may  produce  a  single  response;  or  the  motor 
impulse  may  divide  and  go  out  to  two  or  more  effectors  at 
once.  On  this  basis  we  distinguish  between  simple  and  com- 
pound reflexes. 

In  lower  reflexes  the  adjustment  takes  place  in  the  spinal 
cord  or  in  the  lower  centers  of  the  brain.  When  you  touch  a 
hot  stove,  the  sensory  impulse  upon  reaching  the  spinal  cord 
immediately  passes  over  to  the  motor  side  and  a  motor  im- 
pulse goes  out  directly  to  the  hand,  so  that  you  withdraw  the 
hand  before  you  feel  the  heat  or  pain. 

In  higher  reflexes  the  sensory  impulse  travels  to  a  higher 
brain  center  and  the  adjustment  takes  place  there.  A  sudden 
loud  noise  often  produces  violent  beating  of  the  heart.  The 
sensory  impulse  goes  first  to  the  primary  center  of  hearing, 
then  to  a  higher  center,  and  from  there  part  of  the  impulses 
passes  out  through  a  motor  pathway  to  the  cardiac  muscles. 

A  simple  reflex  involves  a  single  nervous  arc;  the  sensory 
impulses  all  travel  up  through  a  single  sensory  nerve  and  the 
outgoing  impulses  all  proceed  along  one  motor  nerve  and 
affect  a  single  muscle.'     When  we  hear  a  sound  and  auto- 

^  A  number  of  parallel  neurons  in  the  nerve  usually  carry  the  impulse 
inward  or  outward. 


CH.  X] 


VARIETIES  OF  REFLEX 


231 


matically  turn  the  eyes  in  that  direction,  the  action  is  a  simple 
reflex.     [Fig.  71;  cf.  Fig.  16,  p.  41.] 

A  compound  reflex  involves  two  or  more  separate  motor 
nerves.     The  hand-grasping  reflex  is  a  compound  reflex, 


Fig.  71.  —  Simple  Reflex 

Simple  cranial  reflex  from  the  ear  to  the  eye  muscles.  A  sound  stimulates 
the  ear  (A)  and  starts  a  sensory  nerve  impul<ie  along  the  8th  cranial  nerve  to 
lower  auditory  center  (C)  in  the  brain.  The  impulse  travels  to  the  center  for 
eye  movement  (D).  Thence  a  motor  impulse  passes  along  the  6th  cranial 
nerve  (E)  to  the  eye  muscles  (F);  the  muscles  contract  and  the  eye  is  turned 
toward  the  sound.  (A  simple  spinal  reflex  is  shown  in  Fig.  16.)  [After  Her- 
rick.1 


because  it  involves  the  muscles  of  all  the  fingers  and  several 
joints  in  each  finger. 

In  nearly  all  reflex  actions  there  is  a  certain  compounding 
of  impulses  in  the  sensory  part  of  the  nervous  arc.  The  eye- 
wink  is  a  response  to  stimulation  of  the  whole  field  of  vision, 
or  at  least  a  large  area;  the  withdrawal  of  the  hand  from  a  hot 
surface  is  usually  in  response  to  a  temperature  stimulus  that 
affects  many  warmth  receptors  covering  quite  an  area  of  the 
skin.  This  compounding  of  sensory  impulses  is  not  especially 
significant;  it  serves  to  intensify  the  response,  but  seldom 
changes  its  character. 

The  simplest  sort  of  compounding  occurs  in  reflexes  which 
have  two  or  more  motor  effects.  This  is  called  a  distributed 
reflex,   because  the  outgoing   impulse  is    distributed  into 


282 


REFLEX  BEHAVIOR 


[CH.  X 


several  motor  paths.  The  operation  of  a  distributed  reflex  is 
shown  in  Fig.  72.  This  diagram  represents  what  happens,  for 
example,  in  the  pain  reflex. 

A  simple  reflex  may  form  part  of  a  distributed  reflex.    For 
example,  in  the  knee-jerk,  when  the  nerve  impulse  reaches  the 

cord  it  may  divide;  a  por- 
tion may  cross  over  di- 
rectly into  the  cord  or  the 
motor  path  and  cause  the 
leg  to  fly  up,  while  part 
may  travel  up  to  the  brain 
and  produce  some  other 
type  of  activity,  such  as 
grunting  or  flinching. 

If  the  entire  impulse 
reaches  a  higher  center  it 
may  result  in  a  coordinated 
compound  reflex.  Grasp- 
ing, sucking,  and  certain 
vocal  reflexes  are  exam- 
ples of  this.  In  the  grasp- 
ing reflex  of  the  hand  all 
the  fingers  are  bent  at 
once;  the  sucking  reflex  sends  motor  impulses  to  several  dif< 
ferent  muscles  in  the  lips,  cheeks,  and  tongue.  If  the  highei 
centers  come  into  play  the  response  may  be  on  the  opposite 
side  of  the  body  from  the  stimulus;  frequently  it  is  bilateral. 
This  is  due  to  the  fact  that  the  motor  pathways  to  the  two 
sides  of  the  body  are  connected  by  transverse  paths  in  the 
brain. 

Among  compound  reflexes  considerable  importance  at- 
taches to  the  way  in  which  the  different  muscles  are  related. 
We  distinguish  between  antagonistic  reflexes,  in  which  the 
impulses  lead  to  opposing  or  antagonistic  muscles,  and  allied 
reflexes,  where  the  various  muscles  assist  one  another.     In 


Pig.  72.  —  Distributed  Reflex 

Showing  how  stimulation  of  a  receptor  m  the 
skin  leads  to  contraction  of  several  different  mus- 
cles Ml,  M2,  M3.    [From  Herrick.l 


CH.  X] 


VARIETIES  OF  REFLEX 


233 


Table  X. —  Human  Reflexes 
A.  Purest  —  least  subject  to  central  modification  in  adult 


'Pupillary '  or  iris  reflex 

Ear  twitching  (controlled  in  some 

individuals) 
Hand  withdrawal  (to  heat  and  pain) 
Digestive  reflexes  (autonomic) 


Shuddering 

Starting  (to  sudden  noise,  etc.) 
Shivering 
Trembling 

Rhythmic  contractions  (in  epilepsy, 
paralysis  agitans,  etc.) 


B.  Largely  pure  —  subject  to  inhibition  or  reinforcement 


Winking 

Accommodation,  ciliary  reflex 

Eye-fixation  and  convergence 

Hiccoughing 

Sneezing 

Patellar  reflex  (knee-jerk) 

Dizziness  reflexes 

Yawning 

Vomiting 

Facial  reflexes  (to  bitter  taste,  etc.) 

Salivation 

Tickle  reflexes 


Hand  twitching  (to  dermal  pain) 
Plantar  reflex  (to  stimulus  on  sole  of 

foot) 
Great  toe  reflex 

Vasomotor  changes  (blushing,  paling) 
Breathing  changes  (to  specific  stimuli 

and  to  onset  of  sleep) 
Sudorific  reflexes 
Groaning 
Laughing 

Cramp  movements 
Squirming 


C.  Occasionally  pure,  more  often  centrally  modified 
Coughing  Smiling 
Swallowing  and  gulping  Wincing,  etc 
Visceral  discharge,  etc.  Scowling 
Generative  reflexes  Stretching 

Reflexes  to  odors  Convulsive  contractions  (to  deep  pres- 

Gasping  sure  and  heat,  to  pricking  and  other 

Weeping  dermal  pains,  and  to  visceral  pain) 
Sobbing 

D.  Pure  in  infancy,  centrally  modified  in  adult 


Sucking 

Biting  and  grinding 

Spitting 

Hunger  and  thirst  reflexes 

Lip  and  tongue  reflexes 

Vocal  reflexes 

Turning  the  head 

Tossing 

Grasping  (finger  reflexes) 

E.  Posture  reflexes 
Holding  head  erect 
Sitting 


Tugging  (wrist  reflexes) 
Clasping  (elbow  reflexes) 
Reaching  (shoulder  reflexes) 
Kicking  (knee  reflexes) 
Stepping  (gluteal  reflexes) 
Jumping  (ankle  reflexes) 
Sitting  up 
Bending  forward 
Rising 

Standing 
Equilibration 


234     REFLEX  BEHAVIOR  AND  INSTINCT      [ch.  x 

some  cases  the  actions  of  different  muscles  tend  partly  to 
neutralize,  partly  to  reinforce  one  another;  these  are  called 
allied  and  antagonistic  reflexes.  Where  several  reflexes  follow 
in  succession,  they  may  be  alternating,  as  the  two  legs  in  walk- 
ing, or  suppleTuentary,  as  the  flexing  of  the  several  finger 
joints  in  grasping. 

These  relations  emphasize  the  fact  that  a  reflex  is  not  a 
mere  muscular  contraction;  it  is  a  resyonse  to  the  stimulus  — 
it  accomplishes  something.  An  isolated  reflex,  such  as  the 
knee-jerk,  may  not  be  particularly  useful;  but  compound 
reflexes  generally  tend  to  bring  about  some  result  which 
makes  life  a  bit  easier. 

Human  Reflexes.  —  In  human  adults  comparatively  few 
activities  belong  to  the  pure  reflex  type.  Even  such  a  reflex 
as  winking  may  be  reinforced  or  partly  inhibited  by  volun- 
tary control;  and  the  same  motor  paths  that  carry  impulses 
for  the  winking  reflex  also  carry  impulses  for  voluntary 
winking  and  for  closing  the  eye. 

Table  X  shows  the  most  important  human  reflexes  that 
have  received  familiar  names.  There  are  many  others  with 
technical  Latin  names  which  involve  single  muscles  or  whose 
connections  are  somewhat  obscure.  In  some  cases  a  number 
of  similar  reflexes  have  been  grouped  together  under  one  name 
in  the  Table  (e.g.,  the  facial  reflexes).  The  list  is  chiefly 
interesting  as  showing  the  great  variety  of  comparatively 
simple  motor  activities,  and  how  much  more  voluntary  con- 
trol we  have  acquired  over  some  than  over  others. 

-»-!>•  Instinctive  Behavior 

Nature  of  Instinct.  —  The  term  instinct  has  been  variously 
defined.  Earlier  writers  treated  it  as  a  mysterious  innate 
power  possessed  by  subhuman  animals,  which  enables  them 
to  do  the  right  thing  in  the  right  way,  without  consciousness 
or  deliberation.  This  notion  still  prevails  in  popular  psychol- 
ogy.  To-day  we  know  that  instinctive  behavior  is  the  result 


CH.  x]  NATURE  OF  INSTINCT  235 

of  integration  and  coordination  of  nerve  impulses,  and  that 
this  *  central  adjustment '  is  due  to  inherited  nervous  con- 
nections. 

FoUowing  out  this  notion,  instinct  is  defined  as  any  sort  of 
complex  behavior  that  involves  a  set  of  reflex  activities,  in 
which  (a)  one  reflex  furnishes  the  stimulus  that  leads  to  the 
next,  and  in  which  (6)  the  connections  dei>end  ujx)n  inherited 
structure,  not  upon  gradual  learning  by  the  individual.  In 
walking,  for  example,  each  movement  serves  as  a  stimulus 
for  the  next.  \Mien  the  left  foot  touches  the  ground  the 
touch  stimulus,  together  with  the  muscle-sense  stimulus 
from  the  muscles  of  the  left  leg,  starts  the  motor  impulse  for 
lifting  the  right  leg,  and  so  on.  This  succession  of  response 
and  stimulation  is  characteristic  of  instinctive  behavior 
generally. 

In  most  instincts  each  act  in  the  series  involves  a  different 
kind  of  reflex  from  the  preceding.  A  typical  example  is  the 
suckling  instinct  in  the  human  infant.  This  involves  a  suc- 
cession of  different  reflexes :  bending  the  head,  grasping  with 
the  lips,  sucking,  and  swallowing.  Each  reflex  in  the  series 
furnishes  a  stimulus  which  causes  the  next  reflex,  as  already 
pointed  out. *  In  later  life  the  series  is  broken  up,  but  the  last 
link  in  the  chain  still  holds:  when  you  take  food  into  the 
mouth,  especially  if  it  reaches  the  back  of  the  tongue,  it  stimu- 
lates your  swallowing  reflex  so  powerfully  that  you  can 
scarcely  avoid  making  the  swallowing  contractions. 

Instinctive  action  takes  place  because  each  reflex  that  com- 
poses it  follows  an  inherited  path  of  least  resistance,  and 
because  the  motor  response  of  one  reflex  provides  the  appro- 
priate stimulus  for  the  next.  The  development  of  an  instinct 
may  be  thwarted  if  at  any  stage  the  movement  does  not  lead 
to  the  proper  stimulus  for  the  next  stage.  As  a  general  rule 
the  same  fundamental  instincts  appear  in  every  indi\ndual  of 
the  species  at  about  the  same  i>eriod  of  life,  because  they  all 

»P.  22a 


INSTINCTIVE  BEHAVIOR  [ch.  x 

inherit  the  same  fundamental  nerve  structure  and  live  in  sub- 
stantially the  same  environment. 

Origin  of  New  Instincts.  —  Every  species  of  animal,  man- 
kind among  the  rest,  has  evolved  certain  typical  kinds  of 
instinctive  behavior.  Some  instincts  belong  to  a  large  num- 
ber of  species;  others  to  a  single  species.  The  origin  of  wide- 
spread instincts  and  their  special  varieties  is  explained  on  the 
basis  of  natural  selection  in  the  following  way: 

Each  separate  reflex  appears  in  the  first  place  in  connection 
with  some  chance  variation  of  nerve  structure.  The  varia- 
tions that  are  useful  to  a  species  are  selected;  that  is,  because  a 
given  reflex  is  useful  in  keeping  the  creature  alive,  more  and 
more  individuals  having  this  reflex  live  to  maturity;  those 
without  it  are  at  a  disadvantage  and  die  young. 

The  combination  of  reflexes  into  instincts  is  due  to  chance 
variations  in  the  position  of  nerves,  which  bring  certain 
pathways  close  together.  Suppose  some  new  combination  of 
reflex  paths,  brought  about  by  chance  variation  and  capable 
of  inheritance,  is  especially  fitted  to  preserve  the  animal's  life; 
then  the  creature  possessing  this  new  combination  is  more 
likely  to  survive  and  transmit  the  instinct  to  his  oflEspring. 
Not  every  new  combination  is  advantageous.  If  a  variation 
should  occur  in  the  feeding  instinct  of  such  a  sort  that  the 
sucking  reflex  was  not  stimulated  by  lip-grasping,  the  result 
would  be  disastrous  to  the  infant:  he  would  starve  to  death. 
Detrimental  variations  tend  to  weed  themselves  out  by  the 
very  same  selection  that  promotes  the  survival  of  advan- 
tageous variations. 

Human  Instincts.  —  The  human  adult  seldom  behaves  in  a 
purely  instinctive  way.  His  activities  are  largely  modifled 
and  controlled  by  individual  experiences.  Even  the  deep^ 
underlying  instincts  are  partly  suppressed  and  reduced  to 
conventional  forms.  As  we  pass  from  infancy  the  feeding 
instinct  is  greatly  modified  by  the  use  of  our  hands  and  vari- 
ous implements  for  eating.     It  ceases  to  be  a  pure  instinct. 


^.  x]  HUMAN  INSTINCTS  237 

Many  innate  tendencies  never  get  a  chance  to  develop  into 
instincts;  they  are  modified  by  habits  which  are  already 
formed  when  the  tendency  appears;  so  that  what  we  get  is  a 
form  of  behavior  that  is  partly  instinctive,  partly  intelligent. 
The  tendency  to  prefer  the  right  hand  over  the  left,  for 
instance,  does  not  appear  till  after  the  child  has  learned  to 
use  his  hands  in  various  ways.  In  later  life  it  is  diflScult  to 
say  how  much  of  our  right-handedness  is  innate  and  how 
much  is  due  to  training. 

There  have  been  wide  differences  of  opinion  among  psy- 
chologists as  to  the  number  of  human  instincts.  James  and 
others  insist  that  man  possesses  a  great  variety  of  instincts  — 
as  many,  in  fact,  as  any  of  the  lower  species.  Other  writers 
restrict  human  instincts  to  a  few  kinds.  Both  views  are 
partly  correct.  The  human  adult  has  few  yure  instincts,  but 
he  has  a  great  number  of  modified  instincts.  When  we  speak 
of  human  instincts,  it  is  to  be  understood  that  the  behavior 
described  is  not  wholly  inherited,  like  most  animal  instincts, 
but  only  that  it  is  very  largely  determined  by  inheritance. 
In  this  sense  walking  is  a  human  instinct,  though  a  child  may 
be  aided  in  developing  it  by  teaching  and  imitation. 

It  is  convenient  to  classify  human  instincts  according  to  the 

kind  of  results  they  bring  about.    What  objects  in  life  do  our 

various  movements  and  actions  accomplish?    What  purposes 

do  they  serve?    Looking  over  the  field  broadly,  we  find  that 

man  tries  to  attain  one  or  other  of  the  following  results  by  his 

activities : 

Nutrition:  maintenance  of  bodily  organization 
Reproduction:  perpetuation  of  the  species 
Defense:  prevention  of  injury  by  the  environment 
Aggression:  destruction  of  enemies 
Social  organization :  cooperation  with  his  fellows 
Individual  development:  his  own  improvement 

Most  of  these  great  objectives  in  life  give  rise  to  emotional 
expression,  as  we  noticed  in  the  last  chapter.'    They  are,  in 

»P,  214. 


INSTINCTIVE  BEHAVIOR 


[CH.  X 


fact,  the  motives  for  all  our  complex  actions,  whether  emo- 
tional or  not;  they  determine  both  instinctive  and  intelligent 
behavior.  These  six  kinds  of  biological  purposes  serve  as  a 
basis  for  classifying  human  instincts.  Human  beings,  by 
their  inherited  nervous  make-up,  perform  actions  which 
result  in  their  getting  food,  reproducing  their  kind,  warding 
off  destruction,  overcoming  their  enemies,  cooperating  with 
other  men,  and  improving  their  own  condition. 

Table  XI. —  Human  Instincts 


1. 

Nutritive 

2.  Reproductive 

Walking 

Mating  (sexual  attraction,  court- 

Feeding 

ship) 

Wandering  [Hunting] 

Maternal 

Acquiring  [Hoarding] 

Filial  (of  infancy) 

Cleanliness 

Diffused  expression 

3. 

,  Defensive 

4.  Aggressive 

Fighting 

Fighting 

Submission 

Resenting 

Hiding 

Domineering 

Avoiding 

Rivalry 

Modesty  [Shyness] 

Clothing  [Covering] 

Constructing  [Home-ma 

king] 

5 

.  Social 

6.  Individual  Development 

Family  (parental  and  filial) 

Imitativeness 

Tribal  [Herding] 

Playfulness 

'Apopathetic* 

Curiosity 

Sympathetic 

Dextrality  (ri  ght-handedness) 

Antipathetic 

Communicativeness 

Cobperative 

Esthetic  expression 

[Note:  Names  in  square 

brackets  denote  a  more  primitive  form  of  the 

same  instinct.] 

The  principal  human  instincts  are  shown  in  Table  XI. 
Looking  over  the  list  we  recognize  many  familiar  kinds  of 
actions  which  need  no  comment.  The  meaning  of  some-of  the 
others  is  not  so  clear.  The  wandering  instinct,  which  to-day 
finds  expression  in  exploration  and  globe-trotting,  seems  to  be 


CH.  x]  HUMAN  mSTINCTS  239 

derived  from  a  more  primitive  hunting  instinct;  and  the  tend- 
ency to  acquire  property  harks  back  to  a  hoarding  instinct  in 
the  days  when  life  depended  on  storing  away  supplies  for  the 
winter. 

Often  a  single  instinct  includes  several  different  kinds  of 
behavior.  For  example,  fighting  may  be  performed  with  the 
fists  or  the  feet  —  or  even  with  the  teeth.  Part  of  this  diver- 
sity of  expression  is  due  to  the  fact  that  our  inherited  tend- 
ency to  fight  is  developed  this  way  or  that  by  intelligent  learn- 
ing* Diffused  expression  is  the  emotional  display  of  general 
systemic  conditions;  it  includes  the  natural  expression  of 
joy,  grief,  and  the  like.  These  diffused  instinctive  expres- 
sions are  the  only  instincts  in  the  nutritive  group  that  are 
distinctly  emotional. 

The  instincts  belonging  to  the  reproductive  group  develop 
somewhat  later  than  the  others,  due  to  the  slow  maturing  of 
the  generative  organs.  Yet  rudimentary  expressions  often 
appear  at  an  early  age.  Symptoms  of  courtship  are  seen  even 
in  young  children.  Filial  instincts  determine  the  child's  be- 
havior toward  his  parents.  A  child  may  manifest  the  same 
devotion  toward  adopted  parents;  it  is  not  a  question  of 
actual  relationship,  but  of  an  instinctive  tendency  on  the 
child's  part  to  behave  in  certain  ways  toward  those  who 
foster  him.  After  the  fostering  age  is  past,  family  ties  rest 
more  and  more  on  a  social  basis. 

The  defensive  and  aggressive  instincts  are  not  always 
opposite  alternatives,  as  one  might  suppose.  Fighting  and 
fleeing  are  alternative  ways  of  responding  to  the  same  stimu- 
lus; but  many  defensive  instincts  have  no  counterpart  in  the 
aggressive  group.  The  covering  and  home-making  instincts 
in  primitive  man  are  instances  of  this;  they  arose  because 
man  needed  protection  from  rain  and  cold.  In  civilized  man 
these  instincts  have  developed  into  clothing  and  constructing 
tendencies.  The  constructing  instinct  has  had  far-reaching 
results  in  the  sphere  of  invention. 


240  INSTINCTIVE  BEHAVIOR  [ch.  x 

The  clothing  instinct  and  the  modesty  instinct  are  apt  to  be 
confused.  If  we  trace  them  back  to  their  primitive  forms, 
covering  and  shyness,  the  distinction  is  more  obvious.  Shy- 
ness is  connected  with  our  personality;  covering  has  to  do 
with  our  body.  In  civiHzed  life  modesty  is  a  defense  measure 
against  the  attacks  on  our  mental  privacy,  while  clothing  is 
a  means  of  protecting  the  body. 

In  the  list  of  social  instincts  are  included  only  those  forms 
of  behavior  that  are  essentially  social  —  actions  which  are 
neither  defensive  nor  aggressive  but  have  to  do  chiefly  with 
social  organization.  The  family  instincts  are  closely  related 
to  the  mating  instincts  —  tribal  instincts  only  remotely  so. 
Family  life  may  exist  without  community  life,  as  we  find  in 
many  primitive  races. 

The  instincts  called  apopaihetic  (for  want  of  a  better  name) 
are  responses  to  the  attitudes  of  others.  We  tend  to  act 
differently  when  others  are  present,  even  though  they  pay  no 
attention  to  us;  the  bare  fact  of  their  being  around  has  an 
effect  on  our  behavior.  We  respond  in  special  ways  to  the 
approval  of  others,  and  in  other  special  ways  to  their  expres- 
sions of  disapproval. 

The  distinction  between  sympathetic  and  antipathetic  be- 
havior is  too  obvious  to  need  discussion.  We  see  instances  of 
each  almost  daily.  The  only  question  is  whether  this  distinc- 
tion is  innate,  or  whether  the  two  opposing  types  of  behavior 
are  acquired  through  social  intercourse.  There  is  reason  to 
believe  that  the  distinction  rests  on  inheritance.  Certain 
people  please  us  from  the  start,  and  others  are  repugnant.  In 
each  case  the  person  arouses  a,  feeling  in  us.  What  stimulates 
this  feeling?  Usually  some  sensation  —  from  sight,  hearing, 
smell,  etc.  This  man  has  an  attractive  face  or  manner;  that 
man's  voice  pleases  us.  The  external  senses  may  also 
arouse  dislike  —  consciously  or  subconsciously.  The  scarcely 
perceptible  human  body  odor  often  arouses  an  indefinable 
antipathy;  race  antagonisms  are  probably  due  to  this  cause. 


CH.  x]  HUMAN  INSTINCTS  241 

The  cooperative  instincts  are  similar  to  the  tribal  instincts. 
Division  of  labor  to  produce  '  community  results '  is  instinc- 
tive in  the  ants,  where  certain  classes  of  individuals  perform 
various  duties.  In  man  cooperation  is  largely  an  acquired 
trait;  but  it  probably  rests  upon  an  instinctive  basis. 

Instinctive  Tendencies.  —  The  types  of  behavior  connected 
with  individual  development  (Table  XI)  are  not  instinctive 
responses,  strictly  speaking:  they  do  not  represent  definite 
ways  of  acting.  Imitation,  for  instance,  may  be  observed  in 
any  one  of  a  hundred  different  actions;  an  action  is  imitative 
if  it  reproduces  some  other  person's  act,  or  if  it  brings  about  a 
result  which  resembles  some  other  result.  Generally  the 
abiUty  to  imitate  anything  is  acquired  by  a  process  of  learn- 
ing—  it  is  not  inherited.  But  there  are  distinct  inherited 
paths  in  the  nervous  system  which  enable  us  to  try  to  imitate, 
instead  of  responding  in  some  entirely  different  way.  An 
inherited  tendency  to  imitate  is  found  in  some  subhuman  spe- 
cies; the  parrot  tends  to  imitate  speech  and  the  monkey  to 
imitate  gestures.  But  the  parrot  has  no  arrangement  of 
nerve  paths  for  reproducing  gestures,  nor  the  monkey  for 
reproducing  articulate  expression. 

Imitation,  then,  is  not  an  instinct;  but  there  is  in  certain 
species  an  instinctive  tendency  to  imitate.'  The  same  is  true 
of  play  and  curiosity.  They  are  definite  inherited  tendencies, 
which  find  expression  in  various  sorts  of  acts.  The  actions 
themselves  are  not  inherited,  but  they  are  learned  more 
quickly  on  account  of  the  innate  tendency. 

The  imitative  tendency  is  much  stronger  and  more  extensive 
in  man  than  in  any  other  species.  This  is  due  to  the  vast 
system  of  connections  between  the  various  centers  in  the 
human  brain.  We  are  able  to  imitate  not  only  vocal  expres- 
sions (like  the  parrot)  and  gestures  (like  the  monkey),  but 
muscular  movements  of  almost  every  sort  which  we  see  others 
perform.  We  copy  handwriting,  where  we  see  only  the  result 
*  The  tendency  is  imiiativeness;  the  act  is  imitation. 


242  INSTINCTIVE  BEHAVIOR  [ch.  x 

and  not  the  movements  made  in  writing:  we  can  reproduce  the 
form  of  objects  in  nature  by  gestures  or  by  drawing.  Often 
the  imitation  succeeds  only  after  a  more  or  less  elaborate 
course  of  training;  but  the  tendency  to  imitate  is  inherited; 
it  is  based  on  man's  nervous  make-up. 

Play  is  partly  an  imitative  phenomenon.  Children  learn 
to  play  games  by  imitating  other  children;  when  they  play  at 
being  grown  up,  they  imitate  (often  grotesquely)  the  actions 
of  older  people.  But  the  play  behavior  has  also  a  distinctive 
character  of  its  own;  play  means  a  tendency  to  perform  acts 
which  are  not  directly  concerned  with  our  bodily  or  mental 
welfare,  but  which  serve  as  an  outlet  for  our  nervous  energy. 
This  is  characteristic  of  all  play,  whether  imitative  or  spon- 
taneous, social  or  solitary.  Such  widely  different  activities  as 
*  playing  telephone,'  the  game  of  football,  a  solitary  game  of 
«{ards,  a  ramble  in  the  woods,  have  one  common  feature :  they 
\'f  represent  relaxation  from  the  serious  business  of  life. 

Curiosity  is  the  innate  tendency  to  seek  information.  It  is 
deep-rooted  human  trait,  and  distinguishes  man  from  other 
pecies.  The  curiosity  of  dogs  and  other  animals  is  probably 
merely  involuntary  attention  to  very  vivid  stimuli.  The  dog 
is  not  curious  to  explore  the  burrow  in  the  ground;  he  is  held 
there  by  the  odor  which  indicates  the  presence  of  a  rabbit. 
Curiosity  manifests  itself  in  mankind  in  a  variety  of  ways, 
which  differ  according  to  the  individual's  tastes  and  habits  of 
life.  It  may  take  the  form  of  exploration,  study  of  nature, 
delving  into  history,  listening  to  gossip,  and  other  kinds  of 
behavior. 

Right-handedness,  more  properly  called  dexlrality,  is  the 
preference  of  one  hand  over  the  other  in  performing  acts;  in  a 
majority  of  cases  the  right  hand  is  preferred  (dextro-dextral- 
ity),  though  in  many  individuals  it  is  the  left  (sinistro- 
dextrality).  The  tendency  is  supposed  to  rest  on  a  greater 
development  of  certain  motor  centers  in  one  hemisphere  of 
the  brain  and  is  apparently  connected  with  the  formation  of 


CH.  x]  INSTINCTIVE  TENDENCIES  243 

the  language  centers,  which  are  usually  in  the  left  hemisphere. 
The  left  side  of  the  brain  controls  the  right  side  of  the  body, 
and  vice  versa. 

The  tendency  to  communicate  is  not  peculiar  to  man;  it  is 
found  in  gregarious  animals  and  others.  But  in  man  it  is 
unusually  strong.  It  manifests  itself  in  many  ways,  such  as 
gesture  and  speech,  which  are  developed  into  systematic 
modes  of  expression  by  intelligence  through  the  influence  of 
the  social  environment  (ch.  xiii).  Communicative  behavior 
is  greatly  assisted  by  the  development  of  the  language  centers 
in  the  brain,  and  by  man's  upright  posture,  which  leaves  his 
hands  free  to  practice  gesturing  and  writing. 

Esthetic  expression,  the  artistic  touch  which  many  human 
actions  exhibit,  has  not  as  yet  received  a  satisfactory  expla- 
nation. Its  early  manifestation  in  childhood  and  among 
primitive  races  seems  to  indicate  that  it  is  a  real  inherited 
tendency. 

Besides  these  special  instinctive  tendencies,  there  seems  to 
be  a  general  innate  tendency  underlying  each  class  of  instincts. 
We  may  regard  walking,  feeding,  and  the  like,  as  indicating  a 
fundamental  nutritive  tendency.  In  the  same  way  we  note  a 
reproductive,  a  defensive,  an  aggressive,  and  a  social  tendency 
in  human  behavior.  These  are  not  acquired.  They  belong 
to  human  nature;  they  are  based  on  something  in  our  inher- 
ited nervous  constitution. 

Popular  writers  speak  of  an  *  instinct  of  self-preservation.' 
Strictly  speaking  there  is  no  such  instinct.  But  we  have 
inborn  tendencies  to  nourish  ourselves,  to  defend  ourselves, 
and  to  perpetuate  the  species.  Taking  all  these  as  a  part  of 
our  general  inherited  bodily  organization,  it  is  correct  to  say 
that  man  has  a  very  fundamental  instinctive  tendency  to 
keep  himself  alive  and  to  preserve  his  species. 

Development  of  Instincts  in  the  Individual.  —  Instincts  and 
instinctive  tendencies,  like  reflexes,  belong  to  the  inborn  con- 
stitution of  each  individual.     The  nerve  structure  through 


244  INSTINCTIVE  BEHAVIOR  [ch.  x 

which  they  operate  is  provided  for  in  the  original  germ  cell 
from  which  the  individual  grows,  and  is  derived  directly  from 
one  parent  or  both.  This  does  not  mean  that  a  given  instinct 
is  present  at  birth,  nor  that  the  appropriate  nerve  connec- 
tions are  already  formed  at  birth.  The  nervous  structure 
needed  for  many  of  the  instincts  is  practically  ready  at  birth, 
and  in  some  cases  it  develops  long  before:  but  no  instinctive 
action  can  take  place  till  there  is  some  actual  stimulation  and 
until  the  several  reflexes  which  compose  it  are  linked  into  a 
series.  The  welding  of  separate  reflexes  into  an  instinct  is 
often  not  completed  till  a  considerable  time  after  birth. 
Human  walking,  for  example,  is  usually  not  completely  ad- 
justed till  some  time  in  the  second  year  of  life.  This  is 
because  the  muscles  of  the  legs  are  not  sufficiently  developed 
till  then.  The  reproductive  instincts  are  not  fully  developed 
till  somewhere  between  the  tenth  and  fifteenth  years. 

In  short,  any  given  instinct  begins  to  manifest  itself  at  a 
certain  period  of  life,  and  the  period  at  which  it  appears 
depends  not  so  much  upon  the  chance  occurrence  of  appro- 
priate stimuli  as  upon  the  'perfection  of  the  nerve  connections 
and  effector  organs.  If  the  proper  stimuli  do  not  occur  at  the 
right  season,  the  appearance  of  the  instinct  is  delayed,  and  in 
some  cases  it  may  never  be  perfected.  But  since  we  all  live 
in  the  same  general  environment  the  appropriate  stimuli 
usually  do  occur,  so  that  the  instinct  appears  sooner  or  later. 

It  is  sometimes  stated  that  instincts  are  invariable.  This 
is  not  absolutely  true.  Instinctive  movements  are  greatly 
influenced  by  various  stimuli  that  occur  while  the  act  is 
being  performed.  In  the  act  of  walking  we  adjust  our  move- 
ments in  different  ways  when  we  step  up  or  down  or  walk  on  a 
slope,  or  if  we  encounter  a  stone  in  the  path.  Some  of  these 
variations  are  due  to  differences  of  pressure  on  the  sole  of  the 
foot,  others  are  due  to  visual  stimuli  from  the  objects  we  see 
ahead.  Nor  is  this  altogether  a  matter  of  consciousness. 
We  adjust  our  walking  movements  to  slopes  and  obstacles 


V 


quite  as  well  when  we  are  absorbed  in  conversation  as  when 
we  are  paying  strict  attention  to  the  path  in  front.  We  step 
down  from  the  curb  or  walk  around  a  tree,  often  without 
being  aware  that  we  are  doing  so.  There  are  similar  varia- 
tions in  the  instinctive  actions  of  animals  where  there  is  no 
question  of  intelligence.  They  are  due  to  variations  in  the 
stimuli. 

The  chief  difference  between  the  variations  which  occur  in 
instinctive  and  intelligent  behavior  is  that  instinctive  modes 
of  expression  are  not  altered  by  past  experience,  while  intelli- 
gent expression  depends  essentially  upon  the  effects  of  reten- 
tion. 

K  instinctive  expression  is  not  modified  by  experience, 
how  is  it  that  walking  and  feeding  and  other  instincts  show 
the  effect  of  learning?  The  explanation  is  that  in  such  cases 
some  of  the  inherited  paths  or  lines  of  conduction  in  the  nerv- 
ous system  are  broken  up  and  other  pathways  are  substituted. 
To  the  extent  that  this  occurs  the  behavior  Ibses  its  instinctive 
character.  In  the  complex  cortex  of  the  human  brain  the 
higher  centers  gather  in  and  send  out  impulses  which  inhibit 
certain  reflexes  and  reinforce  others.  The  effect  of  this,  as 
time  goes  on,  is  to  transform  our  actions  little  by  little  from 
the  instinctive  to  the  intelligent  type.  In  the  human  adult 
there  are  no  pure  instincts.  Our  behavior  consists  largely 
of  intelligent  actions  which  rest  on  an  instinctive  basis. 
The  instinctive  tendencies  persist  and  develop  along  intel- 
ligent lines.  The  nearest  we  come  to  purely  instinctive 
behavior  is  in  walking,  feeding,  fighting,  and  other  modified 
instincts. 

Summary.  —  Before  examining  motor  experiences  (ch.  xii), 
we  must  study  the  relation  of  responses  to  stimulation. 
Some  responses  are  inherited,  others  are  acquired  by  each 
individual.  By  inherited  is  meant  that  certain  definite 
arrangements  of  nerves  in  the  body  are  determined  from 
the  start;  their  natural  connections  are  such  that  if  a  cer- 


246  INSTINCTIVE  BEHAVIOR  [ch.  x 

tain  stimulus  is  given  a  certain  definite  response  always 
follows. 

The  simplest  inherited  response  is  the  reflex.  A  reflex  is  not 
learned  —  it  is  innate.  Coughing,  winking,  etc.,  are  reflex 
responses;  they  are  the  automatic  outcome  of  certain  stimuli; 
their  nervous  paths  are  inherited. 

An  instinct  is  a  complicated  form  of  response  made  up  of 
a  succession  of  reflexes.  It  is  also  innate.  Instincts  do  not 
necessarily  appear  at  birth.  Any  given  instinct  appears 
when  the  bodily  conditions  for  it  are  ripe.  Besides  instinc- 
tive responses  or  movements  we  have  certain  instinctive 
tendencies.  Imitation  and  other  inherited  tendencies  express 
themselves  in  actions  that  are  not  inherited;  but  the  tendency 
itself  is  innate. 

Man  has  few  pure  instincts.  Most  of  his  inherited  behav- 
ior is  modified  by  learning.  Nearly  all  our  activities  are 
partly  instinctive  and  partly  intelligent.     . 

Practical  Exercises: 

49.  Describe  (or  name)  all  the  different  sorts  of  muscular  movements 
which  you  can  observe  in  your  face  and  head. 

60.  Examine  a  number  of  the  most  familiar  reflexes  given  in  Table  X. 
Test  in  your  case  and  report  how  far  each  is  under  voluntary  control. 

51.  Analyze  the  motor  processes  included  in  three  different  human  in- 
stincts, e.g.,  eating,  walking,  fighting. 

62.  Examine  why  you  have  the  following  tendencies:  (o)  to  sympathize 
with  your  friends;  (6)  to  collect  objects  of  some  kind;  (c)  to  find  out 
things  you  do  not  know. 

63.  Report  all  noticeable  right  and  left  preferences  in  your  actions;  e.g., 
which  arm  or  leg  acts  first  in  putting  on  or  removing  your  various 
garments. 

References: 
On  reflexes  of  infants:  M.  G.  Blanton,  in  Psychological  Review,  1917,  24, 

456-483. 
On  instinct:  W.  James,  Principles  of  Psychology,  ch.  4;  W.  McDougall, 

Social   Psychology,   chs.   2-4,    10-15;   E.   L.   Thorndike,   Educational 

Psychology  (briefer  course),  chs.  3,  5;  J.  Drever,  Instinct  in  Man,  chs. 

7.  8:  J.  B.  Watson,  Psychology,  ch.  7. 


CHAPTER  XI 

INTELLIGENCE 

Individual  Adaptation.  —  If  the  same  stimulus  bp  ap^ied^ 
to  the  same  individual  time  after  time,  his  responses  rday,* 
change.  These  differences  in  the  effect  when  the  external 
causes  are  the  same  do  not  throw  doubt  upon  the  uniformity 
of  nature;  they  mean  simply  that  conditions  loithin  the  organ- 
ism have  changed.  There  are  two  distinct  kinds  of  individual 
modifications  in  responses :  fatigue  and  adaptation. 

(a)  The  fatigue  change  occurs  in  instinctive  actions  and 
reflexes  as  well  as  in  intelligent  actions.  Constant  repetition 
of  the  same  stimulus  causes  wear  and  tear  in  the  receptors, 
synapses,  and  muscles.  There  are  destructive  chemical 
changes  in  the  tissues  which  tend  to  weaken  or  inhibit  the 
usual  response,  so  that  the  outcome  is  different.  If  the  knee 
be  tapped  repeatedly,  the  knee-jerk  gradually  becomes 
weaker.  Fatigue  is  a  condition  of  diminished  efficiency.  In 
ordinary  cases  fatigue  disappears  after  a  period  of  rest,  when 
the  exhausted  tissue  is  restored  by  the  building  up  of  new 
chemical  compounds. 

(6)  Adaptation  acts  in  the  opposite  way.  It  is  not  an  im- 
pairment of  the  response,  but  a  distinct  improvement  due  to 
more  perfect  adjustment.  It  is  due  not  to  destruction  of 
tissue,  but  to  the  formation  of  new  paths  in  the  nervous 
system,  or  to  gradual  improvement  of  the  old  paths  by 
cutting  out  useless  movements.  If  you  are  unfamiliar 
with  shooting,  and  practice  firing  at  a  target,  you  find  after 
awhile  that  you  begin  to  get  better  results.  Your  responses 
become  better  adapted  to  the  situation;  you  make  more 
hits. 

The  adaptation  effect  does  not  wear  away  when  we  rest; 


248  INTELLIGENCE  [ch.  xi 

it  tends  to  persist.  Increased  adaptation  of  response  is  the 
most  notable  characteristic  of  intelligent  behavior,  and  dis- 
tinguishes it  from  instinct. 

Conditioned  Reflexes 

Nature  of  Conditioned  Reflexes.  —  The  simplest  form  of 
acquired  adaptation  occurs  in  reflex  actions.  Under  certain 
conditions  a  response  which  in  the  beginning  was  called  forth 
by  a  certain  stimulus,  may  become  the  response  to  a  totally 
different  stimulus.  The  new  reflex  acquired  in  this  way  is 
called  a  conditioned  reflex. 

Conditioned  reflexes  are  built  up  when  two  stimuli  occur 
repeatedly  at  the  same  time,  one  of  which  (A)  leads  to  a  defi- 
nite and  characteristic  response,  while  the  second  (B)  does 
not.  After  a  number  of  repetitions  of  the  two  stimuU  to- 
gether, if  B  occur  alone,  it  may  bring  about  the  response 
which  originally  belonged  to  A. 

An  example  of  this  is  the  conditioned  knee-jerk.  If  you 
tap  a  certain  spot  just  below  the  knee-cap,  the  leg  flies  up. 
This  is  the  natural  knee-jerk  reflex.  In  certain  experiments 
it  was  arranged  to  strike  the  knee  with  a  hammer  held  and 
operated  by  mechanical  devices  so  as  to  insure  uniform  force 
and  location  of  the  blow.  A  bell  was  sounded  each  time  be- 
fore the  hammer  fell.  During  the  experiment  something 
went  wrong  with  the  apparatus.  The  hammer  fell  part  way 
but  did  not  strike.  Yet  the  leg  flew  up,  just  as  it  was  accus- 
tomed to  respond  to  the  blow.  The  auditory  stimulus  (B) 
brought  about  the  response  which  belonged  originally  to  the 
contact  stimulus  (A).  The  subject  had  formed  a  conditioned 
reflex. 

This  is  a  specially  good  example  because  there  is  no  ques- 
tion of  association  of  ideas.  The  knee-jerk  is  not  under 
voluntary  control;  you  cannot  produce  it  by  suggestion.  In 
other  cases  there  might  be  some  doubt  whether  the  new  con- 
nection was  automatically  acquired;  here  there  is  not,  and 


CH.  xi]  CONDITIONED  REFLEXES  249 

we  may  assume  that  other  simple  conditioned  reflexes  are 
established  in  the  same  automatic  way. 

A  dog  sees  a  box  containing  food  and  smells  the  food;  the 
smell  stimulus  causes  a  response  in  his  salivary  gland  — 
saliva  accumulates  in  his  mouth.  If  the  same  box  be  brought 
in  daily,  a  conditioned  salivary  reflex  will  after  awhile  be 
aroused  by  the  mere  sight  of  the  box.  If  a  bell  be  struck  every 
time  the  box  is  brought  in,  after  awhile  a  conditioned  sali- 
vary reflex  will  be  brought  about  by  the  mere  sound  of  the 
bell,  before  the  box  is  seen. 

This  has  been  definitely  proved  by  Pawlow's  experiment. 
Pawlow  made  an  incision  in  the  dog's  salivary  gland  and 
inserted  a  glass  tube  which  passed  through  the  corner  of  his 
mouth  and  hung  down.  The  saliva  passed  out  through  the 
tube  and  could  be  observed  by  the  experimenter  as  it  dropped. 
The  strength  of  the  conditioned  reflex  was  measured  by  the 
number  of  drops  per  second. 

Conditioned  reflexes  are  found  in  man  just  as  in  lower  ani- 
mals. It  is  probable  that  the  '  watering  of  the  mouth '  at  the 
sight  of  a  juicy  peach  is  a  conditioned  reflex  and  is  not  due 
to  an  association  of  ideas.  Ovu"  response  to  the  dinner  bell 
involves  a  more  complex  mental  process  and  is  not  quite 
analogous  to  the  dog's  conditioned  response. 

The  formation  of  conditioned  reflexes  depends  upon  the 
existence  of  branching  connections  in  the  nervous  system. 
When  two  stimuli  occur  simultaneously  their  nerve  impulses 
may  come  together  in  one  of  the  centers.  If  the  sensory 
nerve  bearing  one  of  these  impulses  has  a  definite  motor  path, 
the  combined  impulses  will  tend  to  follow  that  path.  Sup- 
pose that  at  the  outset  the  sensory  nerve  bearing  the  other 
impulse  has  no  definite  motor  connections  but  its  stimuli 
produce  diffuse  movements  through  one  motor  path  or  an- 
other according  to  the  condition  of  its  various  synapses. 
Then,  by  repetition  the  synapses  connecting  this  sensory 
nerve  with  the  definite  motor  path  of  the  other  will  be 


250  CONDITIONED  REFLEXES  [ch.  xi 

strengthened.  Eventually  the  connection  becomes  so  firmly 
established  that  when  the  *  diffuse  '  stimulus  occurs  alone,  its 
nerve  impulse  will  follow  the  motor  path  of  the  *  reflex ' 
stimulus  and  will  bring  about  the  response  originally  belong- 
ing to  the  latter. 

The  conditioned  reflex  is  the  simplest  type  of  individual 
modification  of  behavior.  It  will  readily  be  seen  that  the 
changes  which  it  brings  about  in  the  animal's  (or  the  man's) 
actions  tend  to  be  adaptive  —  that  is,  to  be  suitable  or  fitted 
to  the  general  situation.  For,  if  two  stimuli  occur  together, 
a  response  suitable  to  both  is  likely  to  be  suitable  to  either. 

Intelligent  Behavior 

Intelligence.  —  When  reflexes  are  altered,  there  are  changes 
in  the  complex  actions  of  which  they  form  part.  Instinctive 
behavior  is  modified  by  the  acquisition  of  conditioned  reflexes, 
and  by  other  changes  to  be  described  later.  In  so  far  as  our 
behavior  is  not  fully  determined  by  inherited  paths  in  the 
nervous  system  it  ceases  to  be  instinctive.^  Complex  actions 
which  are  due  to  individually  acquired  connections  of  nerve 
paths  are  termed  intelligent  actions. 

The  words  intelligence  and  intelligent  are  used  in  psychology 
in  nearly  (but  not  quite)  the  same  sense  as  in  popular  lan- 
guage. Popularly  the  expressions  intelligent  actions  and 
intelligent  behavior  imply  that  we  realize  that  the  actions  in 
question  are  the  proper  thing  to  do.  Psychology  shows  that 
individually  acquired  behavior  tends  to  be  suitable  —  though 
it  is  not  always  so.  It  also  finds  that  we  are  usually  aware  to 
some  extent  of  the  fitness,  but  not  always :  when  we  have  once 
learned  to  perform  a  suitable  act  it  may  be  carried  out  just  as 
automatically  and  unthinkingly  as  an  instinct.  It  is  best, 
then,  not  to  lay  stress  on  the  *  awareness.'  In  psychology, 
intelligent  behavior  is  defined  as  any  complex  action  which  is 
not  inherited,  but  is  acquired  by  the  individual,  provided  the 
1  Instinctive  means  inherited,  innate,  inborn. 


CH.  xi]         NATURE  OF  INTELLIGENCE  251 

response  be  in  any  way  suitable  to  the  situation.^  Intelli- 
gence means  the  capacity  of  an  individual  to  break  away  from 
instinctive  behavior  and  acquire  new  modes  of  action.  In- 
telligence is  often  used  as  a  shorthand  term  for  intelligent 
behavior,  just  as  instinct  is  used  for  instinctive  behavior. 

Although  instinct  is  the  usual  form  of  behavior  in  sub- 
human species,  there  is  a  certain  amount  of  intelligent  adap- 
tation in  all  animals  except  those  low  down  in  the  scale  of  life. 
This  is  shown  by  experiments  with  the  maze.  [Fig.  73.]  An 
animal  is  released  at  the  entrance  (A)  of  a  maze,  food  having 
been  placed  at  the  far  end  or  center  (B).  The  hunger  stimu- 
lus, reinforced  by  the  odor  stimulus,  arouses  him  to  action. 
He  starts  off  and  after  a  certain  number  of  hesitations,  false 
moves,  and  retracings  reaches  the  food  and  satisfies  his 
hunger.  The  same  program  is  repeated  on  the  same  or  suc- 
cessive days.  It  is  found  that  after  a  number  of  trials  the 
animal  succeeds  in  reaching  the  food-box  in  a  shorter  time, 
and  with  fewer  false  moves  as  indicated  by  the  total  distance 
traversed.  In  an  experiment  with  27  white  rats  the  average 
time  was  reduced  from  467  seconds  in  the  first  trial  to  40.3 
in  the  eleventh,  and  the  average  distance  from  4216.1  to 
1029.8  centimeters.  Even  in  species  as  low  as  the  cray- 
fish and  other  Crustacea  there  is  a  slight  reduction  in  time  and 
distance  after  many  trials  in  a  simple  maze. 

The  animal's  behavior  in  the  maze  experiments  consists  of  a 
long  series  of  reflexes  which,  taken  together,  form  a  complex 
action.  The  action  at  first  is  instinctive,  but  it  becomes  mod- 
ified in  the  course  of  time.  The  rate  of  improvement  serves 
as  a  measure  of  the  animal's  intelligence.'^ 

Adaptive  changes  in  behavior  are  not  limited  to  improving 
the  efficiency  of  responses.  The  most  important  changes  are 
those  that  bring  about  new  kinds  of  response.     Human  be- 

^  This  excludes  movements  that  are  entirely  irrelevant,  but  includes  errors^ 
large  and  small,  that  occur  during  the  process  of  learning. 
*  Compare  Table  XII,  p.  260. 


252 


INTELLIGENT  BEHAVIOR 


CH.  XI 


havior  is  far  more  subject  to  this  kind  of  modification  than 
the  behavior  of  any  subhuman  species.     In  the  human  child 


H> 


/   .,.•""'    "\    **\ 

/    .•-     ..•••"     i       *-^.     N   \ 
•,      \     \    \ 

•  '      *      I     :       ••  ••  W  •      *      ;      \     • 

•  .^^  :      •      :     I   •;      '      'I    I.— -«      !— — '. 


Fig.  73.  —  Mazes  for  Investigating  Habit  Formation 

Two  mazes  used  to  determine  the  rate  at  which  an  animal  learns  the  right  path  from  A  to  B. 
Upper  figure  is  a  simple  maze  used  by  Yerkes  with  frogs.  One  choice  of  paths  at  start,  one 
choice  near  end.     (From  Harvard  Pgychological  Studies.] 

Lower  figure  is  a  maze  used  by  Hubbert  with  rats.  Heavy  line  shows  actual  path  of  one  rat 
on  62d  trial.    See  Table  XII  for  results  of  this  experiment.  [From  Jour,  oj  Anxmai  Behavior.] 

we  observe  any  number  of  instances  in  which  new  forms  of 
response  are  developed  through  individual  experience:  talk- 


CH.  xil  NATURE  OF  INTELLIGENCE  253 

ing,  manipulating  knife,  fork,  and  spoon,  buttoning  the 
clothes,  opening  the  door,  climbing  stairs,  folding  the  napkin, 
writing,  swimming,  riding  a  bicycle,  and  many  others.  Adult 
acquisitions  are  generally  concerned  with  more  complex 
processes,  such  as  steering  a  sail-boat  or  motor-car,  type- 
writing, telegraphing,  and  shooting. 

Habit  Formation.  —  Learning,  or  habit  formation,  is  the 
process  of  forming  new  connections  in  the  nervous  arc  and 
perfecting  these  connections  through  repetition.  There  are 
two  rather  different  sorts  of  learning:  (1)  The  formation  of 
inotcyr  habits,  through  coordination  of  muscular  movements  — 
as,  for  example,  learning  to  typewrite.  (2)  The  formation  of 
menial  habits;  this  means  establishing  new  connections  in  the 
brain,  —  connections  which  have  no  immediate  motor  ex- 
pression. When  we  learn  to  notice  weather  signs  or  to 
observe  things  *  out  of  the  corner  of  the  eye '  or  to  think 
logically,  or  when  we  memorize  a  poem  or  the  multiplication 
table,  the  acquisition  is  chiefly  the  forming  of  new  paths  in 
the  brain  centers;  —  there  is  eventually  some  motor  result, 
but  this  is  incidental. 

The  learning  process  is  substantially  the  same  in  motor  and 
mental  habits,  though  the  results  differ.  Both  kinds  of  habit- 
formation  involve  two  steps  or  stages  of  progress:  (a)  Acquisi- 
tion, —  making  new  connections  in  the  nervous  system;  and 
(6)  Fixation,  —  strengthening  these  newly  acquired  connec- 
tions.   These  two  processes  supplement  each  other. 

a.  Acquisition.  —  A  baseball  pitcher  finds  a  way  to  deliver 
a  new  curve  —  one  that  he  has  never  pitched  before.  A 
billiard  player  makes  a  new  kind  of  shot.  A  recruit  in  the 
training  camp  gains  the  ability  to  respond  by  the  proper 
movements  to  each  command  in  the  drill  manual.  In  every 
case  the  first  time  the  new  movement  is  made,  or  whenever 
it  is  altered,  the  man  has  acquired  something.  The  acquisi- 
tion is  not  a  change  in  the  muscles  but  a  change  in  the  nervt 
ous  paths  that   operate  the  muscles.     Intelligent  acquisi- 


254 


INTELLIGENT  BEHAVIOR 


[CH.  XI 


tion  '  of  new  movements  is  the  process  of  forming  new  paths 
of  conduction  in  the  central  part  of  the  nervous  arc. 

Acquisition  does  not  involve  the  growth  of  new  neurons  nor 
the  projection  of  new  collaterals.  The  neurons  and  their 
branches  have  already  been  formed  in  pre-natal  life.  It  is 
only  the  course  of  the  impulse  that  is  changed.  The  acquisi- 
tion of  new  responses  means  that  the  nerve  impulse  is 
shunted  from  the  usual  path  to  some  new  path.  This  means 
that  the  impulse  in  some  part  of  its  course  passes  through  a 
synapse  which  has  not  hitherto  been  used,  instead  of  through 
the  commonly  used  synapse.     In  Fig.  74,  suppose  the  usual 

path  of  the  impulse  be 
>  \      *  '-.^  along  the  neuron  A  and 

out  into  the  neuron  Bl; 
then  if  on  some  occasion 
for  any  reason  the  im- 
pulse passes  over  into 
B2,  a  new  path  of  dis- 
charge is  opened  and  a 
new  response  is  ac- 
quired. 

How  do  these  changes 
of  path  come  about? 
They  are  made  possible 
in  the  first  place  by  the 
existence  of  manifold 
connections  in  the  nervous  system.  There  can  be  no  acquisi- 
tion unless  the  central  neurons  are  provided  with  a  number  of 
collaterals  or  branches,  each  connecting  with  a  different  lower 
or  higher  neuron.  The  several  synapses  leading  out  from  a 
given  neuron  must  vary  in  their  degree  of  resistance,  and 
they  must  be  capable  of  varying  independently,  so  that  at  one 
time  a  certain  synapse  (connecting  with  Bl)  will  be  less 

*  Instinctive  acquisition  is  a  racial  product  and  depends  upon  the  evolu- 
tion of  the  nervous  system  from  generation  to  generation. 


Fic.  74.  —  Changes  of  Path  in  Habit 
Formation 

Diagram  to  illustrate  the  acquisition  of  new  nerve 
paths.  Nerve  impulses  travel  along  A  in  direction  of 
arrows  to  synapses  connecting  with  Bl,  B2,  B3,  B4, 
which  are  alternative  pathways.    (See  text.) 


CH.  xi]  HABIT  FORMATION  255 

resistant  than  any  of  the  others,  at  other  times  another 
synapse  (connecting  with  B2  or  B3).  If  there  are  no 
branches  the  nerve  impulse  will  always  follow  the  same  path; 
and  if  there  are  several  branches  but  a  certain  one  of  the 
synapses  is  always  the  path  of  least  resistance,  then  the  im- 
pulse will  always  follow  that  path. 

Man  has  inherited  an  intricate  system  of  multiple  connec- 
tions in  the  brain  centers  and  particularly  in  the  cortex.  His 
central  nervous  system  includes  a  vast  number  of  alternative 
paths  capable  of  being  brought  into  connection.  This  is  the 
real  cause  of  man's  superior  intelligence  as  compared  with 
other  species. 

But  this  only  means  that  acquisition  is  possible.  The  ques- 
tion still  remains.  How  is  it  actually  brought  about?  The 
actual  change  of  path  in  every  case  depends  upon  changes  in 
the  conditions  of  the  synapses.  There  are  at  least  three  ways 
in  which  we  form  new  paths:  (1)  One  synapse  may  become 
less  resistant  to  the  passage  of  impulse  than  it  was  before; 
or  (2)  the  synapse  that  usually  carries  the  impulse  may 
become  very  resistant,  so  that  this  pathway  is  blocked  and  the 
impulse  passes  over  into  the  next  best  path;  or  (3)  a  very 
intense  impulse  may  succeed  in  breaking  through  several 
synapses  at  once,  just  as  a  powerful  stream  of  water  not  only 
fills  the  usual  channel  but  trickles  over  into  other  channels 
as  well.  It  is  likely  that  the  degree  of  resistance  at  synapses  is 
determined  by  the  quality  as  well  as  the  intensity  of  the  im- 
pulse, and  that  it  depends  also  on  conditions  in  the  next  higher 
neuron  —  the  neuron  into  which  the  impulse  seeks  to  pass. 

These  three  ways  of  altering  the  nerve  paths  give  three 
kinds  of  acquisition:  (1)  Accommodation  occurs  when  a  new 
path  is  opened.  In  reading  aloud,  when  we  see  a  new  word 
the  nerve  impulses  are  shunted  into  new  paths  according 
to  our  retention  and  memory  of  the  several  letters  or  sylla- 
bles composing  the  word;  —  there  is  an  accommodation  of 
response.      (2)  Inhibition  occurs  when  the  old  pathway  is 


^56  INTELLIGENT  BEHAVIOR  [ch.  xi 

blocked.  When  we  see  some  one  coming  who  looks  like  a 
friend  we  prepare  to  greet  him  in  one  of  the  usual  ways;  if 
when  he  comes  closer  he  proves  to  be  a  stranger,  the  path 
of  response  is  closed  and  the  bow  or  greeting  is  inhibited. 
(3)  Diffusion;  the  impulse  may  spread  into  several  paths  si- 
multaneously —  into  new  paths  as  well  as  old.  When  we 
are  walking  to  the  station  to  catch  a  train,  if  we  hear  the  loco- 
motive whistle,  there  arises  a  very  powerful  nerve  current,  due 
to  a  combination  of  the  sound  sensation  and  the  muscle  sen- 
sations concerned  in  walking;  this  causes  the  motor  impulse 
to  spread  into  several  paths;  the  result  is  a  much  livelier 
response. 

Sometimes  these  forms  occur  together.  Inhibition  is  com- 
bined with  accommodation  when  we  start  to  wind  a  clock  the 
wrong  way.  If  the  key  does  not  turn  (inhibition),  we  there- 
upon alter  the  course  of  the  motor  impulse  and  twist  it  in  the 
opposite  direction  (accommodation). 

Most  examples  of  acquisition  drawn  from  every-day  life 
involve  complicated  actions.  To  study  the  process  system- 
atically we  must  start  with  the  simple  reflexes  which  compose 
our  actions  and  observe  how  these  are  modified.  The  con- 
ditioned reflex  is  a  typical  case  of  accommodation.  When 
you  learn  to  check  the  eye-wink,  or  the  cough,  you  are  inhibit- 
ing these  reflexes.  Diffusion  may  be  studied  by  attempting 
to  twitch  the  ear  voluntarily  if  you  have  never  done  so  before. 
The  effort  to  raise  the  ear  causes  the  motor  impulse  to  spread 
to  various  regions  near  by.  You  raise  your  eyebrows,  move 
your  scalp,  etc.  If  the  effort  is  finally  successful,  it  means 
that  the  impulse,  in  spreading,  has  forced  its  way  into  the 
hitherto  unused  pathway  leading  to  the  levator  muscle  of 
your  ear. 

b.  Fixation.  —  Fixation  is  the  process  of  strengthening  the 
connection  in  the  newly  acquired  path.  The  passage  of  the 
nerve  impulse  through  a  new  synapse  tends  to  '  set '  the 
structure  of  that  synapse  so  that  it  offers  less  resistance  in 


CH.  xi]  HABIT  FORMATION  257 

future.  If  only  one  impulse  of  the  sort  occurs  the  effect  tends 
to  wear  away;  the  acquisition  is  lost  and  the  old  response 
returns.  But  if  another  impulse  of  a  similar  sort  occurs  soon 
after,  it  is  more  likely  to  pass  through  the  new  than  through 
the  old  channel.  An  acquisition  becomes  permanently  fixed 
when  the  new  pathway  is  finally  established. 

The  rate  of  progress  in  fixing  a  new  path  depends  upon  four 
factors:  repetition,  intensity,  recency,  and  conflict.  The  new 
path  is  more  firmly  established  in  proportion  to  the  number  of 
times  the  given  stimulus  is  repeated.  Fewer  repetitions  are 
needed  when  the  nerve  impulses  are  very  intense.  The  repe- 
tition is  more  effective  if  the  original  acquisition  occurred 
recently.  These  conditions  of  habit-fixation  correspond  to 
the  three  laws  of  recollection.^  Recollection,  in  fact,  is  just  a 
special  case  of  fixation.  The  connection  between  visual 
impressions  and  verbal  memories  becomes  fixed  in  the  same 
way  as  motor  habits,  so  that  the  sight  of  a  certain  face  leads 
to  the  recollection  of  the  man's  name. 

The  remaining  condition  of  fixation,  the  principle  of  con- 
flict, corresponds  to  the  first  law  of  forgetting.^  The  progress 
of  fixation  is  hindered  if,  meanwhile,  impulses  of  a  different 
sort  occur,  which  use  the  old  pathways.  In  such  cases  the 
old  connection  is  maintained  along  with  the  new,  and  fixa- 
tion takes  longer.  Suppose  when  we  start  to  learn  typewrit- 
ing we  use  two  machines  with  slightly  different  key-boards  or 
with  the  shift-key  in  different  places.  Here  we  have  to  learn 
two  different  resp)onses  to  similar  stimuli.  The  two  responses 
conflict,  and  this  retards  the  progress  of  fixation.  If  we 
attempt  to  memorize  a  poem  in  which  each  stanza  begins 
with  the  same  line  and  then  runs  on  differently,  there  is  the 
same  sort  of  conflict. 

As  the  process  of  fixing  a  habit  goes  on,  two  different 
changes  in  the  behavior  take  place  —  our  actions  are  im' 
proved  in  two  different  ways: 

1  See  ch.  viii,  pp.  186-187.  »  P.  isa 


258  INTELLIGENT  BEHAVIOR  [ch.  xi 

(1)  As  the  new  connections  grow  stronger  there  is  less  hesi- 
tation, so  that  less  time  is  needed  for  performing  the  action. 
This  effect  is  caWed  facilitation  of  the  act. 

(2)  As  the  new  connections  become  stronger  there  are  fewer 
diffused  impulses  along  alternative  paths,  so  that  various 
useless  and  erroneous  movements  gradually  drop  out.  This 
is  called  elimination. 

Law  of  Facilitation  or  Speed:  As  the  newly  acquired 
path  is  strengthened,  the  new  response  tends  to  proceed  more 
rapidly. 

Law  of  Elimination  or  Accuracy:  As  the  new  connec* 
tions  improve,  there  are  fewer  useless  and  erroneous  move- 
ments; the  response  becomes  more  precise  and  more  accurate. 

These  two  types  of  improvement  may  readily  be  observed 
in  the  progress  of  any  complicated  habit,  such  as  typewriting. 
After  you  have  used  the  machine  some  time  you  find  that  the 
movements  follow  more  rapidly.  At  the  same  time  you  will 
find  that  you  strike  fewer  wrong  keys,  and  make  fewer  useless 
movements,  such  as  wrinkling  the  brows,  puckering  the  hps, 
exploring  the  keyboard  with  the  eyes  to  find  a  letter. 

If  you  work  methodically  at  learning  a  new  habit  your 
progress  may  be  measured  quite  exactly  in  terms  of  speed  and 
precision.  The  speed  of  performance  is  reckoned  either  by 
the  amount  accomplished  in  a  given  time  or  by  the  time  re- 
quired to  perform  a  stated  task.  In  learning  to  typewrite,  if 
you  practice  an  hour  a  day,  yoiu-  iinprovement  in  speed  may 
be  measured  either  by  the  number  of  words  typed  in  five  min- 
utes, or  by  the  time  required  for  typing  a  single  page  day  after 
day.  Accuracy  is  measured  by  the  number  (or  percentage)  of 
errors;  in  learning  to  typewrite  you  compare  the  number  of 
mistakes  made  from  day  to  day  in  typing  one  page. 

Experiments  on  the  rate  of  learning  have  been  made  in 
many  common  habits,  such  as  telegraphing,  juggling  three 
balls,  shorthand,  and  mirror-writing.  Fig.  75  shows  the 
progress  of  a  novice  in  learning  to  telegraph.     The  *  curve  ' 


CH.  XI  ] 


HABIT  FORMATION 


f5g 


100 


Pig.  75.  —  Curve  of  Learning 

Shows  the  progress  of  facilitation  (speed)  during  the  fixing  of  a  habit:  learning  to  telegraph. 
Vertical  numbers  denote  the  number  of  words  which  the  learner  was  able  to  telegraph  in  6 
minutes  after  30  minutes  of  practice.  Horizontal  numbers  denote  successive  days.  The  ex- 
perimenter was  entirely  unfamiliar  with  the  habit  at  the  start  [From  Swift,  in  Psychological 
BulUiin.] 


260  INTELLIGENT  BEHAVIOR  [ch.  xi 

(which  is  really  a  jagged  line)  represents  the  number  of  words 
tapped  oflf  in  5  minutes  on  successive  days  with  the  same 
amount  of  daily  practice.  It  shows  the  gain  in  speed,  not  in 
accuracy. 

Table  XII. —  Progress  of  Learning 
A.  Habit  Formation  in  Man: 


tay 

Av.  Time  (sec.) 

Av. 

No 

K  of  Errors 

1 

79 

29 

2 

72 

27 

3 

63 

14 

4 

60 

10 

5 

56 

7 

6 

M 

4 

7 

BS 

2.5 

8 

40 

2 

9 

47 

0.25 

Average  attainment  of  4  human  subjects  learning  to  typewrite  nonsense 
groupings  of  7  different  letters,  arranged  in  a  series  of  55  letters.  The  series 
was  performed  3  times  daily.  Table  shows  average  time  and  average  number 
of  errors  per  series.    (J.  H.  Bair,  Psychol.  Monographs,No.  19,  p.  17.) 

B.  Habit  Formation  in  the  Rat: 


"rial 

Av.  Time  (sec.) 

Av. 

.  Dist.  (cm.) 

1 

467.0 

4216.1 

6 

186.6 

1719.2 

11 

40.3 

1029.8 

16 

25.5 

868.4 

21 

24.2      ,.- 

739.9 

26 

26.1 

756.5 

31 

31.8 

593.2 

Average  attainment  of  27  white  rats  in  maze  experiment.  Two  trials  each 
day;  animal  allowed  to  feed  after  second  trial.  (H.  B.  Hubbert,  J.  of  Animal 
Behavior,  1914,  4,  p.  63.) 

Progress  in  both  speed  and  accuracy  are  shown  in  Table 
XII.  The  upper  table  (A)  shows  the  average  progress  of  four 
men  in  typewriting  nonsense  groups  of  letters.  Their  speed  is 
measured  by  the  time  required  to  typewrite  fifty-five  letters 
and  their  accuracy  by  the  number  of  errors.  The  same  sort  of 
measurements  may  be  applied  to  animal  learning,  though  the 
habits  involved  are  much  simpler.     Table  XII  B  shows  the 


f 


CH.  xij  HABIT  FORMATION  261 

average  progress  of  twenty-seven  white  rats  in  learning  to 
thread  a  maze.  The  speed  is  measured  by  the  time  required; 
in  this  experiment  the  accuracy  is  measured,  not  by  the  num- 
ber of  errors,  but  by  the  distance  covered  by  the  rat  in  his 
wanderings,  which  indicates  the  amount  of  unnecessary  move- 
ment. 

In  some  experiments  on  human  learning  an  interesting  fact 
is  brought  out.  After  a  certain  amount  of  practice  the  prog- 
ress appears  to  cease;  there  is  virtually  no  improvement. 
Then  if  practice  is  continued,  after  a  time  the  man  takes  a  new 
spurt.  If  the  progress  is  represented  by  a  curve,  the  period  of 
,  no-progress  is  a  flat  stretch  between  two  slopes.  This  flat 
part  is  called  a  plateau.  In  Fig.  75  there  is  a  plateau  between 
the  19th  and  30th  days.  Plateaus  are  prnhahly  dn*^  tr>  mir 
having  about  reached  theHimit  of  improvement  -^Kuigh — 
facilitation  and  elimination.  The  new  rise  in  the  curve  indi- 
cates that  another  acquisition  has  taken  place,  which  in  turn 
becomes  gradually  fixed. 

~An  interesting  practical  problem  in  learning  is  whether 
progress  in  fixation  is  more  rapid  when  the  repetitions  are 
crowded  into  a  short  period  of  time  or  when  they  are  spread 
over  a  longer  period  interspersed  with  intervals  of  rest. 
Contrary  to  the  general  impression,  it  has  been  foimd  that 
progress  in  memorizing  is  faster  (in  the  long  run)  with  shorter 
practice  periods,  interrupted  by  rather  long  rest  intervals. 
But  the  progress  in  memorizing  a  speech  is  more  rapid  if  we 
learn  it  as  a  whole  than  if  we  split  it  up  into  parts  and  learn 
each  part  separately.  *-i-i 

Relation  between  Acquisition  and  Fixation.  —  Our  world 
presents  many  constant  and  many  variable  featiu*es.  Cer- 
tain situations  occur  over  and  over  again  with  no  significant 
changes.  Each  morning  we  have  to  dress,  we  breakfast  under 
much  the  same  conditions,  we  pursue  our  regular  occupa- 
tions in  much  the  same  way,  we  are  constantly  meeting  the 
same  people,  we  walk  the  same  streets.    On  the  other  hand 


262  INTELLIGENT  BEHAVIOR  [ch.  xi 

we  vary  our  dress  according  to  the  weather  or  the  occasion, 
we  travel,  we  indulge  in  a  variety  of  recreations,  we  meet  new 
people,  we  find  new  tasks  to  perform.  Most  of  the  situations 
in  human  Ufe  are  too  complex  and  varied  to  be  solved  by 
instinctive  behavior.  Our  inherited  nervous  connections  are 
not  sufficiently  elaborate  to  enable  us  to  perform  the  duties 
of  civilized  human  beings.^  Even  the  simple  act  of  putting 
on  our  clothes  and  buttoning  them  must  be  learned. 

The  variable  situations  in  life  require  acquisition  of  new 
modes  of  behavior,  and  the  constant  situations  need  fixation 
of  responses.  We  must  (1)  adapt  ourselves  continually  to 
new  situations  by  new  acquisitions,  and  we  must  (2)  autom- 
atize many  acts  by  fixation,  in  order  not  to  waste  time  over 
details  that  are  always  the  same.  One  process  is  just  as 
important  as  the  other;  and  both  are  phases  of  intelligence. 

Most  situations  in  life  contain  both  old  and  new  elements. 
When  we  write  a  letter,  we  hold  the  pen  and  manipulate  it  in  a 
stereotyped  way,  but  we  write  different  words  and  sentences. 
We  learn  in  childhood  how  to  write  —  that  is,  how  to  wield 
the  pen.  This  becomes  a  fixed  habit,  so  that  finally  the  act 
of  writing  becomes  as  automatic  as  any  instinctive  act. 

Because  fixed  habits  proceed  automatically,  some  writers 
regard  them  as  cases  of  lapsed  intelligence.  This  is  a  wrong 
notion.  Intelligence  means  capacity  for  adaptation.  Habits 
are  individually  acquired  modes  of  behavior,  and  are  just  as 
suitable  to  the  permanent  factors  in  the  environment  as  new 
reactions  are  suitable  to  new  conditions.  A  habit  is  as  much  a 
display  of  intelligence  as  a  new  response.  There  is  no  lapse  of 
intelligence  in  fixed  habits  —  only  a  decrease  in  the  vividness 
of  the  impressions.  New  responses  (acquisitions)  are  accom- 
panied by  vivid  consciousness,  while  habits  (fixations)  are  not. 
A  deeply  rooted  habit,  such  as  operating  a  pen  in  writing,  is  a 
case  of  lapsed  consciousness  but  not  of  lapsed  intelligence. 

^  Ants  have  an  elaborate  inherited  nervous  equipment,  and  can  meet 
some  very  intricate  situations  instinctively. 


CH.  XI]        ACQUISITION  AND  FIXATION  263 

It  cannot  be  emphasized  too  strongly  that  the  all-important 
fact  in  psychology  is  the  creature's  response  to  the  situation 
which  confronts  him.  Consciousness,  awareness  of  the  situar 
tion,  is  only  one  factor  in  the  process.  If  the  best  results  are 
reached  by  making  the  brain  connections  more  automatic  and 
reducing  the  vividness  of  consciousness  to  a  minimum,  such  a 
condition  marks  a  higher  degree  of  intelligence  than  the  con- 
scious planning  of  every  detail.  The  dressing  habits  formed 
in  childhood  enable  us  to  prepare  for  the  day's  work  more 
rapidly.  We  are  able  to  think  out  some  other  problem  at  th6 
same  time.  Notice  how  much  time  and  effort  is  spent  by  a 
child  who  is  just  learning  to  dress.  Notice  that  in  your  own 
case  the  performance  of  these  stereotyped  actions  may  be 
actually  impeded  if  you  attend  to  each  movement.  In  all 
fixed  habits  subconscious  behavior  is  more  effective,  more 
adaptive,  more  intelligent,  than  conscious  behavior. 

Fixed  habits  always  tend  to  be  adaptive  (or  suitable), 
because  none  but  suitable  actions  are  likely  to  be  repeated 
constantly  and  become  fixed.  But  does  a  new  acquisition 
tend  to  be  adaptive?  Yes  and  no.  If  by  an  acquisition  we 
mean  every  new  variation  that  occurs  in  our  movements  and 
expression,  then  a  large  part  of  our  acquisitions  are  by  no 
means  an  improvement.  We  may  try  a  dozen  times  before 
we  hit  on  the  right  movement  to  accomplish  what  we  are 
after.  But  most  of  these  failures  drop  out  at  once;  they  do 
not  count  as  acquisitions.  The  real  acquisitions  are  those 
that  get  us  somewhere.  These  suitable  acquisitions  are 
selected,  and  tend  to  persist.  The  selection  of  suitable  new 
responses  comes  about  in  two  different  ways:  (1)  through 
trial  and  error  and  (2)  through  associative  memory. 

I.  Trial  and  Error  Learning.  —  Trial  and  error  is  a  process 
which  includes  (a)  persistent  trials  with  wrong  responses,  and 
in  the  end  (6)  accidental  success.  This  type  of  adaptation  is 
found  in  subhuman  species  as  well  as  in  man.  Suppose  a  dog 
is  confined  in  a  yard  with  a  latched  gate.    He  sees  a  cat  out- 


264  mXELLIGENT  BEHAVIOR  [ch.  xi 

side  and  jumps  at  the  gate  time  after  time,  pawing  it  and 
barking  vigorously.  The  gate  holds  despite  his  pawing  and 
barking.  By  chance  his  paw  touches  the  latch-bar  and 
releases  the  latch;  the  gate  flies  open,  and  the  dog  gets  out. 
The  jumping  and  pawing  are  persistent  trials  with  misfit 
responses;  they  do  not  bring  him  to  the  cat.  Pressing  the 
latch-bar  is  an  accidental  variation  of  response  which  brings 
success.  For  the  very  reason  that  it  solves  the  difficulty  it  is 
the  last  to  be  tried;  and  because  it  was  the  most  recent  of  the 
series,  it  is  more  likely  to  recur  than  any  of  the  other  responses 
the  next  time  the  same  situation  is  presented. 

Many  human  habits  are  the  result  of  trial  and  error  learn- 
ing. In  first  learning  to  ride  a  bicycle  we  make  a  lot  of  useless 
movements,  which  wabble  us  zigzag  along  the  road  and  bring 
about  numerous  falls.  These  are  all  responses  to  our  visual 
and  static  sensations.  They  are  not  successful  at  first;  but 
we  persist  and  try  all  sorts  of  variations.  Certain  twists  and 
body  movements  keep  us  upright  and  steer  the  wheel  in  a 
straight  course;  these  responses  are  successful  and  gradually 
supplant  the  rest.  In  a  word,  persistent  trial  is  likely  to  meet 
final  success  by  sheer  chance,  and  the  successful  response, 
being  the  last  in  the  series,  is  more  likely  than  any  other  to 
recur  in  future.  Acquisition  by  trial  and  error,  then,  does 
tend  to  be  adaptive. 

What  goes  on  in  the  nervous  system  during  the  trial  and 
error  process?  The  key  to  the  explanation  is  the  persistence 
of  the  stimuliLS.  In  the  case  of  the  dog  at  the  gate,  the  dog 
sees  and  smells  the  cat  all  the  time.  The  cat-stimuli  keep 
sending  nerve  impulses  to  the  dog's  brain  and  lead  to  a  con- 
tinuous series  of  movements.  The  gate  prevents  the  com- 
pletion of  his  usual  response  —  to  pounce  on  the  cat;  the 
motor  response  is  inhibited  and  finds  some  other  channel. 
The  jumping  and  pawing  movements  are  accommodations  of 
response  due  to  the  increased  resistance  of  certain  synapses 
and  the  lowered  resistance  of  others.    When  the  new  response 


<m.  xi]  TRIAL  AND  ERROR  265 

succeeds,  the  sjniapse  through  which  the  impulse  passes 
remains  a  path  of  lesser  resistance  because  the  situation  is 
solved  and  the  bothersome  stimulus  is  removed;  therefore,  the 
next  time  a  similar  situation  occurs  this  channel  is  more  Ukely 
to  prove  the  path  of  least  resistance  than  the  pathway  through 
other  sjTiapses. 

2.  Associative  Memory.  —  Learning  by  means  of  associa- 
tive memory  is  a  higher  type  of  acquisition.  The  stimuli  do 
not  result  in  trial  responses.  Instead,  the  nerve  impulses 
pass  from  center  to  center  in  the  brain,  arousing  a  succession  of 
images  and  thoughts.  We  pictiu*e  to  ourselves  various  ways 
of  acting;  if  one  course  of  action  does  not  solve  the  difficulty, 
we  picture  another,  and  so  on  till  we  picture  some  action 
which  brings  about  the  suitable  result.  Then  at  last  the 
nerve  impulse  passes  out  into  the  appropriate  motor  channel 
and  we  act. 

An  example  of  learning  through  associative  memory  is  the 
attempt  to  solve  a  chess  problem  or  a  mathematical  puzzle. 
We  think  over  the  various  ways  of  proceeding,  one  after  the 
other.  As  long  as  our  thoughts  fail  to  present  a  satisfactory 
solution,  the  nerve  impulses  continue  their  course  in  the  brain, 
arousing  one  thought  after  another.  When  the  thought  of 
the  correct  solution  arises,  a  motor  impulse  is  started  and 
results  in  action;  the  bothersome  situation  is  gone  and  ceases 
to  stimulate  our  thinking. 

This  method  of  learning  is  called  associative  memory 
because  our  thoughts  depend  altogether  on  the  revival  of 
retention  traces  in  the  brain,  which  arouses  memory  and 
mental  pictures.  Instead  of  actually  making  the  chess 
moves  we  picture  them  mentally,  and  these  pictm-es  form 
trains  of  association  (ch.  xiv).  The  thought  of  the  problem 
keeps  the  impulse  going  rather  than  the  sight  of  the  chess- 
board. Associative  memory  involves  higher  centers  in  the 
brain  and  better  connections  of  the  neurons  than  trial  and 
error  acquisition.    It  resembles  trial  and  error  in  one  respect; 


266  INTELLIGENT  BEHAVIOR  [ch.  xi 

the  last  thought,  which  is  the  successful  one,  is  most  likely  to 
recur  the  next  time  a  similar  situation  is  presented.  So  that 
acquisition  by  the  associative  memory  method  tends  to  be 
adaptive  also. 

Growth  of  Intelligence.  —  Intelligence,  like  instinct,  is  a 
racial  growth.  The  capacity  to  acquire  new  responses  evolves 
gradually  from  lower  to  higher  species  of  animals  as  the 
nervous  system  becomes  more  complex.  But  unlike  instinct 
it  is  also  an  individual  growth.  In  the  human  species  intelli- 
gent behavior  develops  gradually  in  each  individual  and  may 
continue  to  progress  until  far  beyond  middle  life. 

Every  intelligent  act  depends  upon  the  perfection  of  cer- 
tain simpler  acts  which  compose  it.  The  act  of  writing 
depends  upon  our  abihty  to  move  the  fingers  and  wrist  so  as 
to  trace  each  letter  properly.  This  in  turn  depends  upon  our 
ability  to  hold  a  pen  or  pencil.  After  we  have  learned  to 
form  the  letters  by  means  of  certain  wrist  and  finger  move- 
ments we  extend  the  same  act  to  other  muscles,  when  we  write 
large  upon  the  blackboard.^  Certain  elements  in  the  act  of 
writing  are  utilized  in  typewriting  and  typesetting,  while 
other  elements  in  handwriting  are  lacking  in  both  of  these 
acts.  Owing  to  the  intricate  interconnection  of  the  various 
brain  centers  in  man  an  almost  infinite  number  of  new  motor 
combinations  are  possible.  These  new  actions  are  due  not 
merely  to  differences  in  the  stimuli,  as  in  the  case  of  instinct, 
but  to  the  manifold  connections  in  the  brain. 

Human  habits  are  so  complex  that  it  is  difficult  to  classify 
them  satisfactorily.  Some  of  them  fit  into  the  same  general 
types  as  the  emotions  and  instincts.  Our  table  habits  are 
obviously  nutritive;  dressing  and  house-building  are  defensive; 
warfare  is  aggressive  behavior;  educational  acquisitions  are 
habits  of  individual  development.  But  most  habits  belong  to 
several  different  classes.  Games  are  social;  they  are  also 
nutritive  if  they  give  us  bodily  exercise;  or  developmental  if 
»  See  Fig.  80,  p.  368. 


CH.  xi]         GROWTH  OF  INTELLIGENCE  267 

they  exercise  our  thought  processes.  Boxing  is  both  aggres- 
sive and  defensive;  and  it  is  nutritive  when  used  as  a  mode  of 
exercise  —  or  if  we  adopt  boxing  as  a  profession  to  gain  our 
livelihood;  a  friendly  bout  is  social  behavior. 

The  difficulty  of  classification  is  due  to  the  fact  that  intelli- 
gent behavior  represents  a  response  to  the  entire  situation 
which  confronts  the  creature,  rather  than  a  reaction  to  this  or 
that  particular  stimulus.  Intelligence  tends  to  express  the 
organism  as  a  whole,  not  merely  some  special  phase  of  organi- 
zation. There  seems  to  be  no  natural  scheme  of  classifica- 
tion, except  the  very  practical  division  into  useful  and  detrir 
mental  habits. 

Training  of  Habits.  —  Given  a  sudden  emergency,  some 
men  generally  do  the  right  thing,  while  others  always  seem  to 
fall  down.  The  latter  individuals  need  special  training. 
Readiness  to  meet  unforeseen  situations  depends  upon  train- 
ing in  several  phases  of  mental  life.  In  the  first  place,  we 
must  train  our  'perceptions  —  we  must  learn  to  observe 
quickly  and  exactly.  If  we  perceive  instantly  the  real  mean- 
ing of  the  situation,  we  are  in  a  better  position  to  act  properly. 
If  we  can  pick  out  the  significant  details,  we  are  more  likely 
to  see  where  to  direct  our  efforts.  Memory  training  is  also 
important  in  meeting  new  situations.  Few  situations  are 
wholly  new;  the  organization  of  our  memories  will  assist  us  in 
coping  with  situations  that  are  partly  familiar.  The  training 
of  our  thougJit  processes  (ch.  xiii)  is  one  of  the  most  important 
factors  in  adaptation.  And  finally,  training  in  the  fixation  of 
habits  is  essential  even  in  connection  with  new  situations. 

From  the  very  nature  of  the  case  there  can  be  no  special 
training  in  the  '  acquiring  process  '  itself.  The  unexpected  is 
unexpected.  We  can  only  train  the  underlying  processes 
of  observation,  memory,  and  thought,  which  will  render  any 
new  situation  less  strange.  When  we  are  not  confronted  with 
an  emergency  but  with  a  general  problem  of  action,  the 
nature  of  the  acquisition  process  itself  offers  a  helpful  sugges- 


268  INTELLIGENT  BEHAVIOR  [ch.  xi 

tion.  The  trial  and  error  method  is  fundamental,  and  the 
only  way  to  insm-e  success  is  to  stick  to  the  task  —  to  perse- 
vere. The  copy-book  motto,  "  Try,  try  again,"  represents  a 
real  principle  of  mental  activity. 

The  other  side  of  intelligence,  the  fixation  process,  admits 
of  much  more  systematic  training.  The  process  of  strength- 
ening habits  has  been  investigated  in  the  laboratory  and  some 
definite  quantitative  results  have  been  obtained  which  have 
a  practical  value.  We  have  already  noticed  that,  in  certain 
kinds  of  learning,  progress  is  quicker  if  the  practice  periods 
are  comparatively  short,  with  periods  of  rest  in  between. 
These  results  bear  directly  on  the  length  of  study  periods  in 
schools.  How  much  time  should  be  devoted  to  one  subject 
at  a  stretch.?  How  long  should  the  recreation  periods  be,  and 
how  should  they  be  distributed.?  In  recent  years,  much  has 
been  accomplished  in  the  psychology  of  pedagogy,  which  it 
would  take  too  long  to  describe  here. 

The  importance  of  cultivating  useful  habits  can  scarcely  be 
overestimated.  The  habits  involved  in  dressing,  writing, 
table  manners,  and  general  social  intercourse  are  essential  to 
a  well-ordered  life.  We  cannot  respond  to  new  features  in 
the  environment  unless  we  have  developed  habits  which  meet 
the  permanent  phases  of  life. 

A  habit  tends  to  become  detrimental  to  our  welfare  when  it 
is  too  firmly  fixed  to  admit  of  modification,  or  when  it  usurps 
the  place  of  other,  more  useful  responses.  If  we  are  so  wedded 
to  smoking  that  we  must  drop  work  for  a  cigarette  at  impor- 
tant junctures,  or  if  we  are  so  fond  of  telling  anecdotes  that  we 
cannot  readily  listen  to  others,  we  are  likely  time  and  again 
to  lose  certain  business  or  social  advantages.  There  are  also 
mannerisms  and  stereotyped  actions  which  waste  time  and 
energy,  or  which  are  disturbing  to  others.  Nervous  move- 
ments, drumming  with  the  fingers  or  tapping  with  the  foot, 
hemming,  coughing,  and  giggling  are  useless  habits;  a  shrill 
tone  of  voice,  uncouth  table  manners,  whistling  in  public,  and 


CH.  xi]  TRAINING  OF  HABITS  269 

the  like  are  socially  annoying.  All  these  may  be  classed  as 
*  bad  habits  '  from  the  social  standpoint.  Biologically  and 
psychologically  bad  are  such  habits  as  intoxication  or  the 
habitual  use  of  drugs,  which  impair  the  vital  processes  and 
weaken  our  mental  lifci 

The  practical  problem  in  such  cases  is  how  to  break  the 
habit  —  how  to  modify  it  into  a  useful  form  or  suppress  it 
entirely.  This  is  one  of  the  hardest  problems  of  life.  In 
extreme  cases  the  individual  seems  powerless  to  break  the 
habit  by  himself.  Drug  habits  are  especially  masterful 
because  they  produce  a  physiological  state  which  acts  as  a 
powerful  stimulus  to  repeat  the  action;  drastic  measures  by 
others  seem  necessary  to  check  this  class  of  habits. 

Some  habits  can  be  checked  by  substitution.  Nervous 
drumming  with  the  fingers  may  be  broken  off  if  each  time  we 
catch  ourselves  at  it  we  begin  some  other  hand-and-finger 
movement;  or  if  we  turn  to  some  useful  occupation  involving 
the  use  of  the  fingers.  Day-dreaming  may  be  repressed  by 
reading  or  by  trying  to  solve  some  useful  problem.  A  man 
who  smoked  to  excess  broke  the  habit  by  taking  a  long  trip 
where  no  tobacco  was  available. 

Some  habits  can  be  broken  by  interposing  an  irrelevant 
stimulus.  A  sudden  shock  will  sometimes  shunt  the  motor 
impulse  into  other  paths.  This  explains  how  a  bad  habit  is 
often  cured  by  punishment  or  through  the  shock  of  being 
caught  in  the  act.  Mutual  assistance  is  extremely  useful 
here.  If  friends  agree  to  cooperate  in  the  proper  spirit 
progress  is  more  rapid.  Reprimanding  and  ridicuhng  are  apt 
to  produce  bad  effects  even  though  they  break  up  the  habit. 
Habit-breaking  is  such  a  vital  matter  that  a  systematic  study 
of  its  principles  is  well  worth  while.  The  schoolmaster 
should  know  how  to  unteach  as  well  as  to  teach. 

Summary.  —  Intelligence  means  the  ability  to  acquire  new 
and  suitable  forms  of  response  by  individual  modification. 
It  means  changing  our  modes  of  behavior  from  the  inherited 


270  INTELLIGENT  BEHAVIOR  [ch.  xi 

ways  of  acting  to  something  new.  The  simplest  type  of  modi- 
fication occurs  in  the  conditioned  reflex.  A  higher  type  is  the 
transformation  of  instinctive  behavior  into  intelligent  behavior. 
This  requires  a  complex  nervous  system  with  manifold  con- 
nections. 

The  learning  process,  or  habit-formation,  includes  two 
steps :  acquisition  and  fixation.  Acquisition  means  the  per- 
formance of  some  new  response;  in  fixation  we  improve  a  new 
response  by  making  it  more  exact  and  more  rapid.  These 
two  processes  go  together. 

There  are  two  methods  of  learning:  trial  and  error,  and 
associative  memory.  In  the  former  we  persist  in  making 
various  wrong  responses  till  at  last  we  happen  upon  the  right 
one  —  which  tends  to  supplant  the  rest.  In  associative- 
memory  learning  we  think  over  various  solutions  till  we  hap- 
pen to  strike  the  right  one;  this  supplants  the  other  thoughts. 

A  fixed  habit  is  just  as  intelligent  as  a  new  acquisition  if  it 
enables  us  to  meet  the  situations  in  life.  New  acquisitions 
depend  on  our  having  certain  fixed  habits  as  their  foundation. 
A  habit  is  '  bad '  only  to  the  extent  that  it  prevents  new  ac- 
quisitions or  interferes  with  our  individual  or  social  welfare. 

Practical  Exercises: 
54.  Experiment  with  the  formation  of  some  new  habit.    Practice  a  certain 
amount  daily  and  record  your  progress  in  speed  and  accuracy.     [This 
should  be  started  two  weeks  ahead.] 
65.  Make  a  list  of  'useless'  and  'annoying'  habits  observed  in  those 
around  you,  including  some  of  your  own. 

56.  Take  some  trivial  useless  habit  and  try  to  break  it.  Report  the 
methods  used  and  the  degree  of  success. 

57.  Practice  mirror-writing,  looking  in  the  mirror  attentively,  with  your 
hand  concealed  from  direct  view.  Report  any  notable  feature  of  the 
experience. 

58.  Try  to  twitch  your  ears.  Observe  and  report  what  movements  you 
make  in  your  efforts,  and  what  success  you  attain. 

References: 

On  conditioned  reflexes:  J.  B.  Watson,  Psychology,  pp.  2&-38. 
On  learning  and  breaking  habits:  S.  H.  Rowe,  Habit  Formation. 
On  experimental  investigations  of  learning:  E.  L.  Thorndike,  Educational 
Psychology,  vol.  2;  E.  J.  Swift,  Mini^in4ke  Making,  ch.  6. 


/ 


CHAPTER  XII 
VOLITION 


Motor  Experiences.  —  In  chapters  x  and  xi  we  have  exam- 
ined the  different  kinds  of  behavior.  All  behavior  of  what- 
ever sort  is  response  to  some  stimulus.  In  all  complicated 
behavior  there  is  a  central  process  of  adjustment  between  the 
stimulation  and  the  man's  response;  and  in  connection  with 
this  central  nerve  activity  there  arise  sensations,  perceptions, 
and  other  experiences.  When  you  see  a  ball  coming  swiftly 
toward  you,  and  you  step  aside  to  avoid  it,  your  perception  of 
the  ball  is  an  experience  which  arises  in  connection  with  the 
adjustment  process  in  your  brain;  the  perception  takes  place 
ajter  the  stimulus  (the  light  from  the  ball)  strikes  your  eye 
and  before  you  move.  You  perceive  the  ball,  and  then  you 
side-step. 

But  this  is  not  all.  We  know  not  only  what  stimuli  are 
affecting  us  at  a  given  moment,  but  how  we  are  responding 
to  them.  You  are  aware  that  you  are  moving  out  of  the  path 
of  the  ball.  You  get  this  information  through  muscle  sensor 
tions  which  arise  after  the  response  has  begun.  Your  experi- 
ence of  making  the  movements  is  a  very  different  sort  of 
experience  from  your  perception  of  the  ball.  Motor  experi- 
ences are  experiences  of  our  own  movements.  They  are 
stimulated  by  the  contractions  of  our  muscles  when  we  are 
actually  making  the  response;  they  inform  us  about  our  own 
responses  and  not  about  the  stimulus  which  started  the 
response.  This  information  helps  us  to  guide  and  control 
the  progress  of  the  movement. 

Motor  experiences  are  composed  of  kinesthetic  or  muscle 
sensations.  Every  movement,  whether  reflex,  instinctive, 
or  intelligent,  which  involves  muscular  contraction,  gives 


272  CONATION  [ch.  xn 

rise  to  muscle  sensations.'  In  the  case  of  reflexes  these  sen- 
sations are  generally  weak;  they  do  not  form  independent 
experiences,  but  enter  as  marginal  elements  into  some  other 
experience  that  is  present  at  the  time.  We  know  we  are 
winking  or  coughing.  But  the  chief  experience  when  we  wink 
is  a  darkening  of  the  visual  field;  when  we  cough  the  experi- 
ence is  partly  of  hearing  the  sound  of  the  cough. 

In  instinctive  and  intelligent  acts  the  muscle  sensations  are 
more  apt  to  combine  into  definite  experiences;  they  form 
special  sorts  of  experience,  which  are  different  from  any  of 
the  kinds  so  far  considered. 

Conation 

Nature  of  Conation.  —  Our  simple  motor  experiences  are 
usually  not  vivid  and  have  never  received  a  popular  name. 
Psychologists  have  adopted  the  term  conation  for  this  kind  of 
experience.  A  conation  is  an  experience  made  up  largely  of 
motor  sensations.  It  gives  us  direct  knowledge  of  our  own 
bodily  attitudes  and  movements. 

There  are  frequently  other  elements  in  a  conation  besides 
muscle  sensations.  If  the  head  or  whole  body  is  moved,  we 
have  static  sensations  from  the  semicircular  canals.  These 
are  motor  sensations,  though  they  do  not  come  from  the 
muscles.  The  external  senses  also  contribute  to  the  experi- 
ence. You  see  your  arm  moving;  these  visual  sensations 
form  part  of  your  conation.  In  certain  diseases  where  the 
muscle  sense  is  destroyed,  the  patient  is  not  aware  of  his 
movements  unless  he  sees  them;  he  can  move  his  arms  and 
legs  if  they  are  visible,  but  is  unable  to  do  so  with  his  eyes 
shut.  Touch  also  furnishes  information  of  our  movements, 
through  the  rubbing  of  our  clothing  on  the  skin. 

The  special  qualities  of  conation  are  effort,  strain,  and 
resistance;  where  the  static  sensations  enter  in,  there  is  also 
a  nameless  quality  which  may  be  called  whirl.  The  external 
^  Glandular  reflexes  may  produce  systemic  sensations. 


OT.  xn]  NATURE  OF  CONATION  273 

senses  add  no  special  quality  to  the  experience,  but  they  tend 
to  arouse  slight  muscle  sensations  or  images.  We  notice  this 
on  a  train  when  it  starts  smoothly,  or  if  our  own  train  is 
standing  still  and  a  train  close  by  starts  to  move.  The  sight 
of  the  motion  leads  to  an  impression  of  motor  effort  on  our 
part. 

Conations  occur  in  connection  with  reflex  actions,  instinc- 
tive movements,  and  habits.  We  have  reflex  conations  occa- 
sionally, when  a  reflex  action  causes  vivid  muscle  sensations. 
When  we  start  at  a  sudden  noise,  the  movement  arouses  a 
conative  experience.  Coughing  and  sneezing  are  accom- 
panied by  conation.  Usually  the  sensations  arising  from 
simple  reflexes  do  not  give  definite  conations,  but  are  inci- 
dental elements  in  our  perceptions  or  feelings. 

Instinctive  conations  most  frequently  accompany  the  so- 
called  '  nutritive '  instincts,  such  as  wandering,  acquiring, 
cleanliness.  In  other  classes  of  instincts  the  systemic  sen- 
sations are  apt  to  be. more  vivid  than  the  motor;  in  fighting, 
sympathizing,  mating,  and  even  in  modesty  reactions,  the 
experience  is  an  emotion  and  not  a  conation. 

Habit  conations  are  motor  experiences  which  accompany 
the  performance  of  well-established  habits.  We  are  vaguely 
aware  of  our  activity  when  we  are  dressing;  there  is  no  vivid 
experience  of  the  various  movements  unless  we  meet  some 
difficulty,  such  as  a  misplaced  shoe  or  the  loss  of  a  collar  but- 
ton. Then  all  at  once  the  response  ceases  to  be  automatic 
and  the  motor  experience  is  no  longer  a  conation,  but  a 
volition. 

Conations  are  neither  so  vivid  nor  so  important  in  life  as 
perceptions,  memories,  or  feelings.  The  motor  sensations  of 
instinctive  movements  are  usually  overshadowed  by  other 
elements,  so  that  the  experience  is  not  a  true  conation.  If 
the  systemic  sensations  are  strong  the  experience  becomes 
an  emotion;  if  vivid  images  or  thoughts  are  present  it  be- 
comes a  volition.     Intelligent  actions,  except  automatic  hab- 


274  VOLITION  [ch.  xn 

its,  usually  require  thought,  and  their  experiences  rise  to  a 
higher  level  than  conation. 

Volition 

Will  and  Ideomotor  Activity.  —  In  man,  responses  to  stimu- 
lation are  frequently  delayed.  The  intricate  system  of  con- 
nections between  our  various  centers  permit  the  nerve  im- 
pulse to  travel  from  center  to  center  before  it  discharges  into  a 
motor  pathway.  As  the  impulse  passes  through  each  center, 
ideas  are  aroused  corres[K)nding  to  the  memory  traces  re- 
tained in  that  region.  When  at  length  the  nerve  impulse 
discharges,  our  action  is  as  much  an  outcome  of  these  ideas 
as  a  response  to  the  original  stimulus.  Such  responses  are 
called  ideomotor  actions,  in  contrast  to  sensorimotor  actions, 
which  are  responses  to  sensory  stimuli.  If  you  stop  to  think, 
even  for  an  instant,  before  you  act,  your  action  is  ideomotor. 
If  you  are  lying  in  bed  in  the  morning,  vegetating  comfort- 
ably, and  you  suddenly  remember  an  engagement  at  8:30, 
you  jump  up  like  a  flash.  The  movement  is  started  by  the 
thought  —  not  by  a  direct  sensory  stimulus;  it  is  ideomotor. 
If  the  alarm-clock  wakens  you  and  you  jump  out  of  bed,  the 
act  is  sensorimotor  —  the  stimulus  is  a  sensation,  not  a 
thought. 

The  distinction  between  sensorimotor  and  ideomotor  action 
is  not  quite  the  same  as  between  instinctive  and  intelligent 
action.  All  reflex  and  instinctive  acts  are  sensorimotor,  but 
not  all  intelligent  acts  are  ideomotor.  Many  of  our  habitual 
acts  are  quite  automatic;  they  are  sensorimotor,  though  they 
have  been  acquired  by  a  learning  process  and  are  therefore 
intelligent.  Your  response  to  the  thought  of  lateness  is 
ideomotor  and  intelligent.  If  some  one  douses  you  with 
water  or  pricks  you  with  a  pin  and  you  jump  out  of  bed,  the 
act  is  sensorimotor  and  probably  instinctive.  The  man  who 
starts  to  change  his  collar  for  dinner  and  finds  he  has  un- 
dressed completely  and  is  turning  down  the  bed,  is  acting  in  a 


CH.  xn]    roEOMOTOR  VS.  SENSORIMOTOR  275 

sensorimotor  way,  but  the  act  is  not  instinctive;  it  is  a  series 
of  actions  which  he  has  learned  —  acquired  individually  — 
and  has  reduced  to  a  perfect  habit;  in  fact,  the  habit  is  alto- 
gether too  perfect. 

The  kind  of  experience  which  accompanies  ideomotor 
actions  is  called  volition  or  loill.^  A  volition  is  a  complex 
experience  made  up  chiefly  of  two  sorts  of  elements:  motor 
sensations  and  ideas.  When  we  vxiU  to  do  a  certain  thing,  we 
have  a  thought  of  the  action,  together  with  certain  muscle 
sensations  of  effort  or  memories  of  such  sensations.  Voli- 
tions are  generally  more  vivid  than  conations. 

Volition  is  especially  important  in  life  because  the  idea 
which  starts  the  action  is  an  anticipatory  image  or  purpose; 
it  represents  what  we  are  going  to  do.  Suppose  you  plan  a  trip 
to  the  mountains  and  afterwards  take  the  trip.  When  you 
make  the  journey  you  produce  actual  movements  and  receive 
sensations  which  correspond  to  the  image  experiences  that 
you  had  in  making  your  plans  beforehand.  Just  so  far  as  you 
accomplish  what  you  planned  to  do  you  bring  the  events  of 
the  outer  world  under  your  own  control.  You  think  of  a 
certain  situation,  and  as  a  restdt  of  your  actions  this  situar 
tion,  which  you  previously  thought  of,  is  finally  brought 
about.  Your  will  has  changed  the  course  of  events  in  the 
outer  world. 

The  actual  working  of  ideomotor  activity  is  often  misunder- 
stood. It  is  commonly  supposed  that  the  idea  of  a  movement 
tends  to  produce  that  very  movement  —  that  the  idea  directs 
the  nerve  impulse  into  the  proper  motor  path.^  This  is  not 
the  case.  There  is  no  inherited  or  natural  connection  between 
the  idea  of  a  given  movement  and  its  execution.  Every  idea 
tends  toward  some  expression ;  but  the  exact  sort  of  expression 
is  in  the  beginning  a  matter  of  chance.     It  may  be  any  sort 

I  Strictly  speaking, 'will'  is  the  capacity  for  ideomotor  activity;  'volition' 
is  the  experience  which  accompanies  the  action;  the  act  itieif  is  'voluntary.' 
*  Even  so  acute  an  observer  as  James  held  this  view. 


276  VOLITION  [ch.  xn 

of  movement.  There  is  no  inherited  adaptive  connection 
in  volition  as  there  is  in  reflexes. 

When  you  will  to  pick  up  a  book,  you  grasp  it  at  once. 
But  this  is  the  result  of  a  habit;  there  is  no  inherited  tendency 
to  pick  up  a  book  when  you  will  to  do  so.  This  is  evident  if 
you  watch  a  very  young  child  trying  to  pick  something  up. 
He  fumbles  about,  and  even  if  he  finally  succeeds,  the  act  is 
performed  awkwardly;  he  has  not  yet  learned  to  connect  up 
the  idea  with  the  proper  motor  impulse.  Watch  a  child  try- 
ing to  copy  the  letters  of  the  alphabet  or  trying  to  draw  a 
picture.  Or  try  yourself  to  perform  some  action  which  you 
have  never  learned  to  do,  such  as  twitching  your  ears.  The 
idea  is  vivid,  and  it  results  in  various  movements,  but  it 
does  not  issue  in  the  movement  which  you  willed. 

All  ideomotor  responses  must  be  learned;  the  proper  con- 
nections between  brain  centers  and  motor  paths  are  acquired 
by  trial  and  error.  In  adult  life  all  our  ideas  of  action  lead  to 
the  appropriate  movements  except  in  rare  cases,  such  as  ear- 
twitching.  This  is  because  the  right  response  has  already  been 
selected.  If  the  child  thinks  of  picking  up  a  book,  and  the 
right  movement  happens  to  follow,  the  muscle  sensations 
reinforce  the  idea  and  make  this  particular  nervous  connec- 
tion stronger  than  others,  so  that  the  next  time  the  proper 
motor  impulse  is  more  likely  to  follow  the  idea.  In  this  way 
our  volitions  come  to  be  followed  by  just  the  movements  we 
want  to  make.     The  ability  is  not  inherited,  but  acquired. 

Volition  is  a  distinct  advance  over  the  kinds  of  experiences 
which  we  have  so  far  examined.  It  anticipates  what  is  going 
to  happen.  The  will  is  not  (like  perception,  memory,  and 
emotion)  concerned  chiefly  with  the  reception  of  information 
from  the  outer  world  or  from  our  own  bodies,  but  with  action 
by  the  individual  upon  the  environment.  The  volition  experi- 
ence leads  to  voluntary  activity,  which  is  a  great  step  toward 
control  of  the  physical  world  by  living  beings.^ 

^  Instinctive  behavior  involves  some  control  over  nature.  Volition 
increases  this  control  tremendously. 


CH.  xii]  VOLUNTARY  ACTIVITY  277 

Voluntary  Activity.  —  Voluntary  activity  is  distinguished 
from  other  activity  by  deliberation  and  choice.  The  latent 
period  between  the  stimulus  and  response  is  longer.  The 
delay  is  due  to  the  fact  that  the  motor  expression  is  checked 
and  a  train  of  ideas  take  place  before  the  action  begins. 

The  deliberation  which  precedes  voluntary  acts  is  not  al- 
ways long.  The  length  of  the  latent  period  depends  on  the 
nature  of  the  situation.  An  intricate  course  of  action,  such 
as  the  choice  of  your  career  in  life,  generally  requires  a  long 
time  to  think  out.  But  such  situations  are  comparatively 
rare.  Most  of  our  voluntary  acts  are  decided  quickly.  The 
latent  period  is  often  very  short.  When  you  are  reading  a 
book  and  the  dusk  gathers,  you  suddenly  notice  that  it  is  too 
dark  to  read  without  great  effort.  Immediately  you  get  up 
and  turn  on  the  light.  There  is  no  apparent  delay.  Yet  the 
act  does  take  longer  than  a  simple  sensory  response.  The 
sensory  response  to  this  situation  would  be  to  drop  the  book 
and  close  the  eyes;  in  voluntary  action  this  immediate  re- 
sponse is  checked  and  the  idea  of  lighting  follows;  there  is  a 
slight  delay  before  you  act. 

The  choice  which  takes  place  in  voluntary  actions  is  due  to 
the  complexity  of  the  nerve  impulses.  When  our  motor 
expression  is  checked  or  inhibited,  various  ideas  follow  in 
succession,  each  representing  some  different  course  of  action. 
When  at  length  one  of  these  becomes  so  strong  that  it  leads 
to  nervous  discharge  along  some  motor  path,  the  result  is  a 
voluntary  movement.  On  a  holiday  morning  my  first  *  plan  ' 
is  to  spend  the  day  reading  in  the  library.  The  bright  spring 
weather  suggests  a  motor  trip  through  the  country.  The 
motive  of  duty  suggests  finishing  a  half-written  article. 
Finally,  the  thought  of  a  long,  brisk  walk,  combining  pleas- 
ure with  exercise,  proves  the  most  powerful  impulse,  and  my 
voluntary  activity  proceeds  along  this  line. 

Volition  is  selective,  not  because  it  determines  events  which 
are  otherwise  indeterminate,  but  because  it  tends  to  bring 


278  VOLITION  [ch.  xn 

about  the  fittest  actions,  instead  of  the  most  obvious.^  In  any 
response  the  path  of  motor  discharge  is  along  the  line  of  least 
resistance,  but  in  voluntary  action  the  nerve  impulses  in  the 
brain  pass  from  center  to  center  before  the  motor  impulse 
starts;  and  during  this  period  of  suspense  we  think  of  the 
various  alternatives.  As  a  result  of  the  delay  and  of  the 
changes  in  the  central  nerve  impulses,  the  action  when  it  does 
start  tends  to  be  more  suitable  than  an  immediate  response 
would  be. 
J.  Relation  of  Volition  to  Intelligence.  —  We  have  distin- 
guished two  sorts  of  motor  experiences:  (1)  Simple  motor 
experiences  or  conations,  which  are  made  up  chiefly  of  muscle 
sensations;  and  (2)  Volitions,  composed  of  muscle  sensations 
and  ideas.  These  two  are  alike  in  that  they  give  us  informa- 
tion about  our  motor  attitudes  and  the  movements  we  are 
making,  and  so  enable  us  to  guide  the  course  of  our  move- 
ments and  control  our  actions.  You  keep  on  walking  or 
steering  your  bicycle  or  tying  your  necktie  because  you  are 
kept  informed  every  instant  as  to  how  your  movements  are 
progressing.  Motor  experiences  have  a  different  meaning  in 
our  lives  from  perceptions  and  memories  of  external  objects 
or  from  feelings  of  our  own  systemic  conditions.  These 
other  experiences  are  chiefly  receptive;  motor  experiences 
not  only  tell  us  what  we  are  doing  but  suggest  the  way  we 
shall  act. 

Leaving  out  of  account  simple  reflexes  and  autonomic 
activities,  human  behavior  is  mainly  of  two  sorts :  instinctive 
acts  and  intelligent  acts.  Instinctive  behavior  is  inherited; 
that  is,  we  inherit  nervous  paths  and  connecting  synapses 
which  enable  us  to  perform  these  actions  without  a  course  of 
learning.  Intelligent  behavior  is  not  inherited;  we  do  not 
inherit  definite  paths  and  connections  for  this  type  of  action, 

^  The  question  whether  the  will  is  free  has  been  debated  for  ages  and  has 
not  yet  been  finally  settled.  It  is  not  so  important  a  problem  if  we  empha- 
size the  delay  factor  and  the  notion  of  fitness. 


CH.  xii]      RELATION  TO  INTELLIGENCE  279 

but  merely  the  possibility  of  making  these  new  connections 
(among  others)  by  acquisition  and  fixation. 

A  distinction  must  be  made  between  the  way  we  acquire  the 
ability  to  perform  an  act  and  the  way  we  perform  it.  Instinct 
and  intelligence  are  two  different  ways  of  acquiring  motor 
ability.  Instincts  are  racially  acquired;  habits  are  individu- 
ally acquired  —  that  is,  they  are  learned.  But  once  a  habit  is 
acquired,  the  way  we  actually  perform  the  act  may  be  just 
like  an  instinct.  In  other  words,  not  all  of  our  intelligent  acts 
are  performed  voluntarily.  Some  highly  intelligent,  adaptive 
actions  are  sensorimotor;  the  motor  experience  which  accom- 
panies them  is  a  conation,  not  a  volition.  This  is  the  case 
when  the  action  has  been  completely  fixed  or  established. 

Most  of  our  actions  in  every-day  life  are  a  mixture  of  old 
and  new  movements.  We  rarely  meet  an  entirely  new  situa- 
tion, nor  yet  a  situation  without  some  new  element.  Most 
situations  are  partly  a  repetition  of  familiar  circumstances, 
but  with  something  in  them  which  is  quite  different  from 
anything  we  have  experienced  before  in  the  same  connection. 
So  our  responses  are  largely  automatic.  But  if  they  are  to 
suit  the  situation  they  must  be  partly  voluntary  also.  Re- 
moving the  collar  is  a  fixed  habit;  but  whether  we  shall  put 
on  a  fresh  collar  or  continue  undressing  depends  on  other 
factors  in  the  situation.  This  requires  thought  and  voli- 
tion if  our  response  is  to  be  suitable. 

Volition  is  useful  only  so  far  as  the  situation  is  new  or 
ambiguous.  It  impedes  the  performance  of  a  stereotyped 
habit  to  attend  to  each  movement  closely.  Intelligence 
means  attention  to  the  branch-points  and  alternatives  of 
behavior,  with  voluntary  control  of  behavior  at  these  points; 
intelligence  also  means  inattention  to  stereotyped  actions 
and  letting  them  proceed  automatically,  without  voluntary 
control. 

Training  the  Will.  —  Voluntary  actions  are  most  effective 
when  we  act  after  the  proper  amount  of  deliberation.     In 


280  VOLITION  [ch.  xii 

childhood  we  must  learn  to  inhibit  too  hasty  action.  "  Think 
before  you  act,"  is  the  maxim  commonly  taught  to  children, 
and  with  good  reason.  The  child  tends  to  act  at  once,  on 
the  mere  perception  of  the  situation.  He  must  be  taught  to 
avoid  impulsive  action  —  that  is,  action  in  which  the  motor 
impulse  follows  immediately  upon  stimulation.  Emotional 
expression  (weeping,  kicking,  etc.)  is  restrained  and  con- 
trolled by  admonition  and  punishment.  The  will  to  refrain 
is  taught  first;  the  will  to  act  comes  later. 

In  adult  life,  if  restraint  has  been  properly  cultivated,  the 
emphasis  is  on  the  other  side.  Too  much  deliberation  leads 
to  a  vacillating  attitude.  We  should  cultivate  the  habit  of 
sizing,  up  the  possibilities  quickly  and  then  acting  without 
nee^ss  delay.  The  ordinary  situations  of  life  are  clear 
enough  for  quick  decision.  Long  deliberation  is  apt  to  lead  to 
a  habit  of  day-dreaming  —  of  living  in  a  fictitious  world. 
Its  pathological  manifestation  is  aboulia,  a  condition  where 
the  patient  is  unable  to  reach  any  decision  at  all. 

In  popular  psychology  *  will  power  '  means  the  capacity  to 
go  ahead  and  keep  going  ahead  in  a  motor  way.  The  strong- 
willed  man  is  one  who  pushes  his  purposes  to  completion 
regardless  of  obstacles.  He  is  not  discouraged,  whatever 
happens.  Even  physical  pain,  the  greatest  deterrent,  will 
not  turn  him  aside.  We  read  of  the  Spartan  boy  who  was 
gnawed  by  a  fox  which  he  had  brought  to  school  concealed  in 
his  clothing,  and  yet  by  sheer  strength  of  will  kept  a  passive 
countenance  and  showed  no  signs  of  his  agony.  As  a  modern 
parallel  might  be  cited  the  American  governor  of  Cuba,  who 
stuck  to  his  post  and  fulfilled  his  administrative  duties  faith- 
fully for  days,  despite  a  raging  fever. 

These  instances  show  the  power  of  vivid  thought  (the  pur- 
pose idea)  to  keep  one  steadfast  in  vigorous  action  or  in  self- 
restraint.  He  who  is  trained  to  control  his  actions  by  steady 
purpose  and  grit  is  best  able  to  cultivate  useful  habits  —  and 
to  break  bad  habits.    If  the  thoughts  '  I  will '  or  '  I  will  not ' 


CH.  xiil  TRAINING  THE  WILL  281 

find  strict  motor  obedience,  one  need  not  fear  being  over- 
mastered by  any  habit. 

Training  the  will  gives  us  greater  ability  to  resist  sugges- 
tion. This  does  not  mean  that  if  some  one  advises  us  to  do 
a  thing  we  should  promptly  refuse.  The  majority  of  sug- 
gestions from  those  about  us  are  probably  reasonable  and 
deserve  consideration.  But  neither  should  we  promptly 
acquiesce.  Voluntary  decision  requires  at  least  an  instant 
of  deliberation.  If  we  fall  into  the  habit  of  following  a 
certain  person's  suggestion  ivithout  hesitation,  we  become  the 
agents  of  his  will,  not  our  own.  This  may  have  no  bad  effect 
on  us  if  this  particular  person  is  conscientious  and  competent, 
so  long  as  he  is  there  to  guide  us.  But  when  the  master-mind 
is  removed  we  are  in  sore  diflBculty  if  we  have  lost  our  self- 
reliance  and  power  of  self-guidance. 

This  is  especially  to  be  remembered  in  the  home  training  of 
children.  Parents  who  insist  upon  immediate,  unreasoning 
obedience,  are  fitting  their  children  to  be  the  slaves  of  others. 
If  the  training  is  effective  —  if  it  makes  the  child  perfectly 
docile  —  he  will  develop  into  a  type  of  which  his  parents  will 
not  be  proud.  If  he  inherits  the  same  *  masterful  '  traits 
which  prompts  them  to  treat  him  this  way,  he  will  rebel  and 
the  attempt  will  fail.  Training  in  obedience,  in  conforming 
to  social  conventions,  is  an  essential  part  of  the  child's  educa- 
tion. But  when  he  reaches  the  reasoning  age,  parents  and 
teachers  should  not  expect  unreasoning  obedience.  It  is  the 
parent's  duty  to  show  the  why  and  the  wherefore  of  his  com- 
mands, and  to  cultivate  in  the  child  the  spirit  of  challenge. 
This  seems  the  only  way  to  avoid  one  of  two  unfortunate  out- 
comes :  either  a  hopeless  obedience  to  suggestion,  with  a  min- 
imum of  will-power,  or  an  unsocial  obstinacy. 

Ideals 

Natiire  of  Ideals.  —  An  ideal  is  a  very  complex  experience 
in  which  ideas,  systemic  sensations,  and  motor  sensations 


282  IDEALS  [ch.  xii 

are  all  prominent.  It  consists  of  a  vivid  image  or  thought, 
together  with  an  intense  feeling  and  a  strong  tendency  to  act. 
If  one's  ideal  is  to  become  a  physician,  he  has  a  general  image 
or  thought  of  the  various  characteristics  of  the  medical  pro- 
fession; he  is  stirred  by  a  noticeable  feeling  when  he  thinks  of 
what  a  doctor  can  accomplish;  and  his  acts,  with  their  accom- 
panying motor  sensations,  are  such  as  will  tend  to  fit  him  to 
become  a  capable  physician.  In  other  words,  an  ideal  in- 
volves thinking  a  thing,  feeling  it,  and  doing  it. 

Ideals  generally  grow  up  by  degrees  out  of  particular  expe- 
riences in  which  one  or  other  of  these  different  elements  pre- 
dominates. Our  deepest-rooted  ideals  are  usually  formed 
slowly  and  are  related  to  a  host  of  separate  experiences. 
The  experiences  which  develop  into  ideals  are  due  largely  to 
social  stimulation.  We  are  told  that  we  are  fitted  for  a  cer- 
tain career;  or  the  ideal  may  be  aroused  by  contact  with  some 
one  who  has  been  successful  in  this  particular  line  of  work,  or 
it  may  be  strengthened  by  meeting  some  one  who  has  made 
a  conspicuous  failure  in  some  other  fine  that  appealed  to  us 
as  an  alternative. 

Ideals  are  of  the  utmost  importance  in  human  life;  but 
their  importance  consists  in  their  persistence  and  pervasive- 
ness rather  than  in  their  vividness.  They  stick  to  us  through 
thick  and  thin,  but  we  rarely  experience  them  as  distinct  and 
vivid  states  of  mind.  Usually  they  are  marginal  or  subcon- 
scious. They  are  underlying  motives  of  actions,  and  are  usu- 
ally noticeable  only  in  the  attitudes  which  we  assume  (ch.  xv). 

Summary.  —  The  various  kinds  of  behavior  discussed  in  the 
two  preceding  chapters  give  rise  to  motor  experiences.  Mus- 
cular contractions  stimulate  muscle  sensations;  these  and 
our  static  sensations  are  combined  into  experiences  of  our 
own  activity.  Motor  experiences  are  divided  into  conations 
and  volitions.  A  conation  is  a  simple  experience  which  accom- 
panies reflexes,  instincts,  and  fixed  habits.  It  is  usually  vague 
and  unimportant. 


CH.  xn]  SUMMARY  283 

A  volition  is  an  experience  composed  of  motor  sensations 
and  ideas;  the  ideas  are  anticipation  images  or  purposes, 
which  in  the  course  of  time  are  put  into  effect.  The  con- 
nections in  the  nervous  system  between  the  will-impulse  and 
the  appropriate  movements  are  not  inherited,  but  acquired. 
The  special  features  of  will  are  the  delay  (with  deliberation) 
and  choice.  The  actions  which  follow  a  volition  are  called 
ideomotor  actions. 

An  ideal  is  a  composite  experience  which  includes  ideas, 
feelings,  and  motor  sensations.  Ideals  are  rarely  vivid; 
they  usually  form  underlying  attitudes,  which  are  of  prime 
importance  in  life. 

Practical  Exercises: 

59.  Analyze  the  motor  experiences  of  laughter. 

60.  Describe  the  chain  of  experiences  involved  in  picking  up  a  book, 
especially  the  muscle  sensations. 

61.  Test  your  ability  to  inhibit  each  of  the  reflexes  in  lists  A  and  B,  of 
Table  X  (p.  233).  Also  try  which  of  them  can  be  brought  about 
voluntarily. 

62.  Examine  your  experiences  when  you  are  planning  some  course  of 
action,  such  as  how  to  spend  a  holiday. 

63.  Trace  the  development  of  your  ideal  of  what  yoiur  career  should  be. 

References: 

On  volition:  W.  James,  Principles  of  Psychology,  ch.  26;  W.  McDougall, 
Social  Psychology,  chs.  9,  16. 

On  ideas  and  movements:  M.  F.  Washburn,  Movement  and  Mental  Imag- 
ery; E.  L.  Thorndike,  in  Psychological  Review,  1913,  20,  91-106. 


CHAPTER  XIII  ^^7 

LANGUAGE  AND  THOUGHT 

Communication.  —  So  far  we  have  considered  a  man's 
experiences  as  something  belonging  to  himself  alone,  and  as 
having  no  connection  with  the  experiences  of  other  human 
beings.  As  a  matter  of  fact,  the  experiences  of  one  member 
of  the  community  frequently  aflFect  others  very  decidedly. 
Ideas  are  passed  along  from  one  individual  to  another.  The 
communication  of  impressions  has  an  important  bearing  on 
our  mental  development.  In  many  cases  we  can  shorten  the 
process  of  learning  considerably  by  the  simple  expedient  of 
having  some  one  else  tell  us  what  to  do.  "  Keep  your  mouth 
closed  and  hold  your  head  lower,"  says  the  swimming 
teacher,  and  the  process  of  learning  to  swim  is  much  simpU- 
fied  by  the  communication  of  these  ideas. 

There  is  a  popular  notion  that  one  mind  sometimes  in- 
fluences another  directly,  without  the  medium  of  the  nerv- 
ous system  and  receptors.  There  is  at  present  no  satisfactory 
evidence  that  this  direct  communication  ever  takes  place. 
We  get  ideas  from  other  persons  by  means  of  indications 
which  they  express  in  words  or  gestures;  and  these  indications 
are  always  received  through  our  ears  or  eyes  or  some  other 
sense  receptor.  What  one  reads  in  popular  magazines  and 
novels  about  telepathy  can  be  dismissed  as  highly  improbable. 

Communication  is  an  important  factor  in  mental  life.  It 
not  only  enables  us  to  learn  rapidly,  but  it  furnishes  us  with 
a  great  store  of  ideas  which  no  single  individual  could  gather 
during  his  limited  life-time  by  his  own  unaided  efforts. 
Besides  all  this,  communication  and  social  intercourse  are  the 
means  of  building  up  two  new  sorts  of  experience:  language 
and  thought. 


CH.  xm]  COMMUNICATION  285 

Language  is  an  experience  made  up  of  the  same  kind  of  ele- 
ments as  volition.  Both  volition  and  language  are  composed 
of  ideas  and  motor  sensations.  But  language  leads  to  a  very 
different  kind  of  response  from  volition.  In  the  case  of 
volition  the  response  is  some  direct  effect  on  the  general 
environment;  in  language  the  response  is  some  gesture  or 
vocal  expression  which  arouses  an  idea  in  some  other  person 
and  brings  him  into  relation  with  the  speaker.  Voluntary 
action  enables  you  to  open  a  closed  door  by  turning  the  knob 
with  your  hand.  But  if  the  knob  does  not  work,  you  call 
out,  "  Open  the  door,"  and  this  language  response  on  your 
part  may  induce  some  one  inside  the  room  to  turn  the  key 
and  let  you  in.  Language  responses  often  bring  about  indi- 
rectly the  same  result  that  volitional  responses  bring  about 
directly. 

A  thought  is  a  special  kind  of  idea  which  developed  in  the 
first  place  as  an  aid  to  communication.  You  may  have  a 
vivid  memory  of  some  event  in  your  life;  but  unless  you  are 
an  artist  you  cannot  reproduce  this  in  picture  form  for  the 
benefit  of  others.  You  can  only  communicate  it  by  means  of 
arbitrary,  conventional  symbols.  If  you  have  seen  the 
Natural  Bridge  and  wish  to  describe  it  to  a  friend,  you  do  so 
by  means  of  visible  symbols  (by  writing  a  series  of  words) 
or  audible  symbols  —  by  saying  *  bridge  '  and  uttering  other 
conventional  sounds  which  call  up  corresponding  ideas  in  his 
mind.  Your  friend  reads  your  letter  or  listens  to  your  de- 
scription, and  this  arouses  in  him  an  idea  of  the  Natural 
Bridge  which  is  more  or  less  like  your  own  idea. 

The  sound  of  the  word  *  bridge  '  in  no  way  resembles  a  real 
bridge;  and  the  written  word  bridge  does  not  look  like  a 
bridge.  But  by  repeated  association  between  the  spoken  or 
written  word  and  the  object,  the  word  calls  up  the  memory 
image  of  the  object,  and  in  the  course  of  time  the  word  tends 
to  replace  the  image,  so  that  we  represent  the  bridge  in  terms 
of  words  instead  of  by  a  mental  picture  of  the  thing  itself. 


286      LANGUAGE  AND  THOUGHT   [ch.  xin 

Ideas  whose  prominent  elements  are  words,  instead  of  images, 
are  called  thoughts.  Thoughts  are  arbitrary,  conventional 
representations  which  take  the  place  of  mental  pictures 
(images)  of  objects  and  events. 

Language  and  thought  belong  to  a  higher  level  than  other 
experiences.  They  involve  the  growth  of  several  new  adjust- 
ing centers  in  the  cortex  of  the  brain.  These  two  types  of 
experience,  language  and  thought,  grow  up  together.  Speak- 
ing and  thinking  in  words  depend  on  the  accumulation  of 
traces  in  one  or  more  of  these  special  centers.  If  you  speak 
a  word  you  hear  the  sound  of  your  own  utterance,  so  that  the 
spoken  word  is  intimately  connected  with  the  thought-word. 
The  greater  the  number  of  words  in  a  language,  the  more 
acute  is  the  thinking  in  the  community  using  that  language. 

We  find,  then,  that  language  and  thought  are  composed  of 
ideas  and  motor  sensations;  and  that  they  have  a  number  of 
peculiar  characteristics,  which  are  not  found  in  the  experi- 
ences noticed  in  previous  chapters.  (1)  Language  and 
thought  depend  on  communication  between  individuals. 
Primitive  man  speaks  with  reference  to  some  listener:  he 
learns  to  think  in  words  through  repeatedly  uttering  words  for 
social  purposes.  (2)  Language  and  thought  form  a  higher 
grade  of  experience  than  perception,  memory,  emotion,  and 
the  rest;  they  involve  the  development  of  special  centers  in  the 
brain.  (3)  Language  and  thought  are  symbolic;  that  is,  they 
are  arbitrary,  conventional  signs  —  not  mental  copies  of  what 
they  represent.  Except  in  rare  cases  the  sound  and  the 
written  letter  do  not  resemble  the  thing  for  which  they  stand. 

Symbolic  Experiences.  —  The  last-mentioned  character- 
istic distinguishes  thought  from  other  sorts  of  ideas.  A 
memory  is  virtually  a  reproduction  of  some  definite  percep- 
tion. Fancies  and  general  images  consist  of  bits  gathered 
together  from  various  perceptions.  The  distinguishing  mark 
of  a  general  image  is  that  it  reproduces  in  a  sketchy  way  the 
appearance  of  some  class  of  objects. 


CH.  xiii]         SYMBOLIC  EXPERIENCES  287 

It  would  not  be  easy  to  draw  pictures  similar  to  our  general 
ideas  every  time  we  wished  to  communicate  with  others;  so 
instead  we  make  some  arbitrary  sound  or  gesture  which  takes 
the  place  of  the  picture.  A  certain  sound  or  gesture  comes  to 
be  habitually  associated  with  the  idea  of  a  tree,  another  with 
the  idea  of  a  man,  and  so  on;  through  constant  association  the 
conventional  sound  or  gesture  tends  to  become  more  and 
more  a  part  of  the  idea.  Among  civilized  men  this  associa- 
tion is  so  strong  that  the  arbitrary  sound  produced  by  utter- 
ing the  word  tree,  for  instance,  becomes  the  chief  element  in 
our  general  idea  of  a  tree.  We  think  of  trees  chiefly  in  terms 
of  the  sound  or  vocal  utterance  of  that  word;  the  mental 
picture  of  the  tree  tends  to  become  more  and  more  vague. 
In  this  way  thoughts  tend  to  displace  general  ideas  in  our 
mental  experience.  Thinking  is  largely  a  series  of  word- 
pictures  —  not  of  object-pictures.  We  think  in  terms  of 
words  and  sentences,  which  do  not  resemble  the  things  we  are 
thinking  about.  Words  are  arbitrary  signs  or  symbols  which 
we  use  instead  of  calling  up  the  '  copy  '  every  time. 

Thought  is  an  outgrowth  of  language.  One  can  readily 
call  up  memories  and  general  images  of  the  things  he  has 
experienced.  In  all  ordinary  situations  of  life  we  could  prob- 
ably work  out  our  ideas  by  means  of  mental  pictures  without 
using  any  symbolic  terms.  There  seems  no  reason  why  a 
sohtary  man  should  have  devised  the  words  tree  and  cow  to 
help  him  in  thinking  about  trees  and  cows.  The  fact  that 
some  of  us  think  aloud  when  alone  is  no  argument;  we  are 
simply  exercising  a  firmly  established  habit.  There  is  evi- 
dence that  castaways  gradually  lose  the  power  of  ready 
speech;  their  thinking  probably  reverts  more  and  more  to  the 
*  image  '  type.  It  is  social  situations  that  lead  to  the  inven- 
tion of  words,  and  to  their  use  as  ideas  in  p'ace  of  imagery. 

The  Different  Kinds  of  Language.  —  The  principal  kinds  of 
language  are  gesture,  speech,  and  writing.  Each  finds  expres- 
sion in  a  special  type  of  behavior:  gesturing  makes  use  princi- 


288  LANGUAGE  AND  THOUGHT        [ch.  xiii 

pally  of  the  hands  and  head;  speaking  uses  the  mouth  and 
throat;  writing  uses  the  hands  and  some  instrument  which 
leaves  a  permanent  mark  on  stone,  paper,  etc.  Facial  expres- 
sion is  a  more  primitive  type  than  any  of  these,  but  it  is 
generally  an  expression  of  emotional  states  and  is  rarely  used 
for  communication.  Winking  an  eye  er  smiling  at  some  one 
may  be  treated  as  facial  gesturing. 

Gesture  language  probably  arose  earlier  than  speech.  It 
came  from  the  practice  of  pointing  to  objects  or  waving  the 
arms  to  arouse  attention.  In  time  many  of  these  gestures 
assumed  a  conventional  form.  Certain  movements  of  the 
hand  and  head  came  to  denote  fish,  fruit,  meat,  fire,  cooking; 
pairs  of  opposite  movements  came  to  signify  assent  or  dis- 
sent, or  *  come  here  '  and  *  go  away.'  Gesture  language  is 
still  used  among  the  deaf.  Otherwise  it  has  been  almost 
wholly  superseded  by  speech. 

Vocal  language  is  much  more  convenient  than  gesturing. 
One  can  easily  speak  when  engaged  in  fishing  or  plowing, 
while  gestures  are  apt  to  interfere  with  these  occupations. 
One  can  listen  to  oral  conversation  without  turning  the  head; 
it  is  not  easy  to  watch  the  plow  and  a  companion's  gestures  at 
the  same  time.  The  ears  are  always  open;  we  can  secure  a 
man's  attention  to  what  we  say  without  stepping  in  front  of 
him  or  seizing  hold  of  him,  —  though  some  people  do  not  seem 
to  realize  this.  In  the  sick  room  gesturing  may  be  more 
effective;  but  in  ordinary  situations  speech  has  all  the 
advantages. 

The  various  languages  or  tongues  which  have  grown  up 
among  mankind  —  Greek,  English,  French,  etc.  —  all  belong 
to  the  same  mental  type:  vocal  expression.  They  differ  only 
in  the  special  words  that  are  arbitrarily  associated  with  each 
object  or  meaning.  Associations  of  ideas  formed  in  early 
childhood  are  most  likely  to  persist;  so  that  if  one  starts  life 
in  an  English-speaking  community,  the  English  word-associa- 
tions are  deeper  rooted  than  those  acquired  later.     A  young 


CH.  xra]         VARIETIES  OF  LANGUAGE  289 

child  may  easily  be  taught  three  or  more  languages  and 
remain  master  of  them  all.  Later  in  life,  verbal  associations 
are  more  diflScult  to  form;  languages  learned  after  the  adoles- 
cent period  are  rarely  so  well  organized  or  so  thoroughly 
assimilated.  It  is  not  known  whether  each  tongue  develops 
a  special  center  in  th^  speech  region;  but  we  know  that  the 
associations  between  words  of  the  same  tongue  are  closer 
than  between  those  of  different  tongues. 

Written  (graphic)  language  is  used  in  civilized  communities 
to  supplement  speech.  It  consists  in  making  permanent 
marks  or  impressions  upon  stone,  bricks,  papyrus,  or  paper. 
In  the  older  graphic  languages  the  records  were  rude  pictures 
of  objects;  later  these  pictures  became  conventionalized,  as  in 
Chinese,  or  each  graphic  unit  came  to  symbolize  a  syllabic 
sound,  as  in  syllabary  Japanese.  In  the  graphic  language  of 
modern  western  races  each  symbol  represents  an  elementary 
vocal  sound,  either  consonant  or  vowel.  The  letters  of  our 
alphabet  are  symbols  for  vocal  sounds  which  are  themselves 
arbitrary  symbols  for  objects.* 

There  are  several  varieties  of  graphic  language.  Besides 
ordinary  handwriting  may  be  mentioned  printing,  typewrit- 
ing, telegraphy,  and  phonography.  In  all  these  forms  the 
characteristic  feature  is  the  permanent  record,  which  makes 
it  possible  for  one  person  to  communicate  with  others  at  great 
distances  or  after  long  intervals  of  time.  In  fact  the  chief  use 
of  graphic  language  is  to  extend  the  range  of  communication 
in  space  and  time.  Graphic  language,  like  gesture  language, 
is  received  visually,  except  the  phonographic  variety,  which 
is  auditory.^ 

Nearly  all  graphic  languages  are  asymmetrical.  In  the 
Greek  and  Latin  alphabets  the  record  always  runs  from  left  to 

*  Our  numerals  are  not  vocal  symbols,  but '  ideographs.'  The  number  1492 
conveys  the  same  meaning  to  all  men,  whatever  their  tongue. 

'  Books  for  the  blind,  printed  in  raised  letters,  are  perceived  by  the  sense 
of  touch. 


290  LANGUAGE  AND  THOUGHT        [ch.  xiii 

right,  in  Hebrew  and  Arabic  from  right  to  left,  in  Chinese 
from  top  to  bottom.  The  order  is  practically  never  reversed, 
nor  are  indlA  idual  letters  turned  around.  '  Mirror-script '  is 
unintelligible  to  most  persons,  and  it  is  usually  difficult  to 
write.     [Fig.  76.]    This  is  due  to  long  fixation  of  habit;  if  you 


jX/AjL'^-fr-  -  ',,' 


Fig.  76.  —  Reading  Mirror  Script 

Unkss  one  is  practiced  in  reading  reversed  writing  it  is  difficult  to  recognize  and 
read  a  single  word  of  this.     Hold  it  before  a  mirror  and  the  writing  is  plain. 

practice  sufficiently  you  can  learn  to  write  and  read  reversed 
script  quite  readily.  The  direction  in  which  we  write  may 
possibly  be  due  to  the  sort  of  instrument  originally  used  by 
our  ancestors  in  handwriting:  a  quill  is  more  easily  pulled 
along;  a  chisel  is  more  effective  when  pushed;  a  brush  is  more 
naturally  swept  down  toward  you. 

Understanding  and  Reading.  —  Communication  is  a  two- 
sided  affair.  It  is  not  completed,  like  other  types  of  behavior, 
when  the  resjxjnse  is  made;  after  the  first  person  A  speaks, 


CH.  xiii]       UNDERSTANDING;  READING  291 

there  is  a  receptive  process  on  the  part  of  another  person  B. 
The  spoken  words  produce  complex  sound-waves,  which 
stimulate  B's  ear.  The  effect  of  these  verbal  stimuli  is  very- 
different  from  that  of  other  sounds.  There  is  first  a  sound- 
perception  process  in  B's  auditory  center;  then  the  nerve 
impulse  passes  into  his  auditory-speech  (word-hearing) 
center,  where  word-perception  occurs.  This  arouses  in  B  a 
thought  similar  to  the  thought  experienced  by  A  as  he  utters 
the  words. 

The  arousing  of  thought  in  a  second  person  by  speech  or 
writing  is  called  understanding.  When  B  gets  A's  thought,  he 
understands  what  A  is  trying  to  communicate.  There  is  no 
special  English  term  for  receiving  and  understanding  spoken 
words  and  gestures;'  but  the  process  of  receiving  and  under- 
standing written  language  is  known  as  reading.  Reading  is 
more  under  our  own  control  than  the  reception  of  spoken 
words.  We  can  move  the  eyes  slowly  or  rapidly  so  as  to 
regulate  the  speed  of  receiving  the  stimuli;  we  can  glance 
back  and  read  a  sentence  over  again. 

In  reading,  the  sensory  elements  are  not  prominent.  We 
perceive  the  total  word,  not  the  individual  letters.  If  there 
is  an  imperfection  in  one  of  the  letters,  we  usually  do  not 
notice  it,  and  often  a  wrong  letter  in  a  word  passes  unnoticed. 
Even  the  most  expert  proofreader  may  overlook  these  errors. 
The  general  meaning  of  the  sentence  suggests  the  thought, 
and  if  some  letter  or  trivial  word  is  omitted  the  imagination 
supplies  the  gap.  The  same  is  true  in  speech,  though  not  to 
the  same  extent. 

Our  failure  to  detect  such  errors  is  due  to  the  fact  that 
understanding  involves  a  double  mental  process,  which  almost 
smudges  out  the  individual  sensations.  A  word-stimulus  is  a 
sound  or  a  visual  effect.  It  is  perceived  like  other  stimuli; 
and  just  as  in  every  kind  of  perception  the  piecemeal  sensa- 
tions merge  into  a  general  total  effect.  But  after  this  there  is 
^  It  may  be  called  comprehension  or  listening. 


292  LANGUAGE  AND  THOUGHT        [ch.  xiii 

a  further  working  over  of  the  material  in  the  higher  verbal 
centers,  which  transforms  it  still  more.  This  effect  is  noticed 
if  we  listen  to  some  one  speaking  alternately  in  English  and  an 
unknown  tongue.  We  get  the  same  effect  in  reading  if  we 
come  across  some  unknown  foreign  word  or  phrase.  The 
unfamiliar  words  are  heard  or  seen  plainly,  but  they  do  not 
arouse  ideas;  they  are  merely  sounds,  or  marks  on  the  page. 

Reading  aloud  is  a  further  complication  of  the  communica- 
tion process.  The  reader  acts  as  a  relay  between  the  author 
who  expressed  the  thought  originally,  and  the  persons  who 
receive  it.  It  is  quite  possible  for  you  to  transmit  thought 
without  understanding  it  yourself,  if  you  read  aloud  in  an 
unknown  tongue.  You  can  even  learn  to  read  aloud  mechan- 
ically in  your  own  tongue,  thinking  of  other  things  all  the 
while,  but  giving  the  right  accent  and  intonation  to  the  sen- 
tences. 
y  Brain  Centers  for  Language  and  Thought.  —  There  are  four 
special  brain  centers  concerned  in  language  and  thought: 

(1)  a  word-uttering  or  speaking  center  for  vocal  language; 

(2)  a  word- writing  center  for  written  language;  '  (3)  a  word- 
hearing  center  for  understanding  word-sounds  and  for  audi- 
tory thought;  and  (4)  a  word-seeing  center  for  reading  and 
for  visual  thought. 

These  centers  are  found  in  only  one  side  of  the  brain  — 
usually  the  left  side  —  whereas  the  other  centers  are  found  in 
both  hemispheres.  ^  The  location  of  these  four  higher  centers 
is  shown  in  Fig.  77.^  The  word-hearing  center  lies  near  the 
auditory  center  in  the  left  temporal  lobe  of  the  cortex;  the 
word-uttering  (speaking)  center  lies  in  the  left  frontal  lobe 

^  It  is  possible  that  the  *  gesture '  center  is  distinct  from  this. 

'  In  cases  of  paralysis,  if  the  left  side  of  the  body  is  paralyzed  the  indi- 
vidual's capacity  for  thinking  and  speaking  are  usually  quite  normal;  but  if 
the  right  side  is  affected  some  of  the  language  functions  are  apt  to  be  im- 
paired.   The  right  side  of  the  body  is  controlled  by  the  left  side  of  the  brain. 

•  Cf.  Figs.  13,  14.  Recent  investigation  indicates  considerable  individual 
differences  la  the  location  of  these  centers. 


CH.  xm 


SPECIAL  BRAIN  CENTERS 


near  the  region  which  controls  movements  of  the  tongue,  lips, 
and  throat.  These  two  regions  are  connected  together  by 
association  tracts.  Vocal  language  ordinarily  involves  co- 
operation of  the  two.  If  the  word-hearing  region  is  destroyed 
the  patient  is  unable  to  understand  the  meaning  of  words,^ 


KlAMaC 


Pig.  Tl.  —  Language  Centers  in  the  Cortex 

Diagram  of  cortex  of  the  left  hemisphere;  front  of  the  head  is  at  kft  of  the 
drawing.  Speaking  or  word-uttering  center  is  in  frontal  lobe  near  centers 
for  moving  tongue,  lips,  and  jaws.  Writing  center  is  near  centers  for  mov- 
ing fingers.  Word-bearing  or  auditory  language  center  is  in  temporal  lobe 
near  the  center  for  hearing.  Reading  or  word-seeing  center  is  in  occipital 
lobe  near  the  visual  center.     (Cf.  Figs.  IS,  14.) 

though  not  deaf  to  sounds  in  general.  He  may  be  able  to 
utter  words  through  other  connections.  If  the  word-uttering 
center  is  destroyed  the  patient  is  unable  to  speak,  though  he 
may  understand  the  meaning  of  words.  This  disorder  is 
called  TTwtor  aphasia. 

In  the  case  of  deaf  persons  who  have  been  taught  to  si>eak 
and  to  *  read  the  lips,'  a  connection  is  developed  between  the 
word-uttering  center  and  some  center  in  the  visual  region. 
The  popular  term  deaj-mute  is  incorrect.  A  deaf  man  is  mute 
merely  because  the  connections  between  lip>-word  seeing  and 
word  uttering  have  not  been  trained.  These  connections 
are  harder  to  form  than  between  hearing  and  uttering 
^  This  disorder  is  called  aenaory  aphasia. 


294  LANGUAGE  AND  THOUGHT        [ch.  xiii 

words,  but  under  proper  treatment  they  can  be  readily  de- 
veloped. 

The  word-seeing  (reading)  center  lies  near  the  visual  region 
in  the  occipital  lobe  of  the  left  hemisphere.  Destruction  of 
this  area  causes  inability  to  read  {alexia).  The  patient  sees 
the  letters,  but  they  do  not  convey  any  meaning  to  him,  — 
just  as  an  Arabic  or  Chinese  inscription  appears  to  us  only  as 
a  miscellaneous  collection  of  marks.  The  word-writing  center 
lies  in  the  frontal  lobe  near  the  center  which  controls  hand 
and  finger  movements.  Its  destruction  causes  inability  to 
write  (agraphia).  These  two  centers  are  not  so  closely  con- 
nected as  the  two  vocal-speech  centers.  Destruction  of  one 
function  is  not  so  likely  to  involve  disturbance  of  the  other. 
In  fact  the  word-seeing  center  is  more  closely  connected  with 
the  word-uttering  center  than  with  the  word-writing  center. 

The  Different  Kinds  of  Thought.  —  The  ideas  of  civilized 
man  consist  largely  of  verbal  thoughts.  For  most  of  us  the 
word  *  horse'  is  the  main  feature  of  our  idea  of  a  horse.  We 
picture  vaguely  the  appearance  of  horses,  their  movements, 
the  sounds  they  make  in  galloping  or  neighing;  but  the  focus 
of  the  idea  is  the  word. 

For  some  persons  a  word  is  chiefly  a  sound.  For  others  it  is 
the  muscle  sensations  from  the  lips,  tongue,  and  throat  in 
speaking  For  others  it  is  the  looks  of  the  printed  word.  In  a 
few  cases  it  may  be  the  muscle  sensations  from  the  hand  in 
writing.  So  there  are  these  four  different  kinds  of  thinking: 
auditory,  vocal-motor,  visual,  and  hand-motor.  We  classify 
people  according  as  their  thinking  belongs  to  one  or  other  of 
these  types.  But  in  many  cases  a  man's  thinking  may  com- 
bine two  or  more  of  these  elements :  your  thought  of  a  horse 
may  include  both  the  sound  of  the  word  and  the  motor  sen- 
sations of  uttering  it. 

When  you  think  in  terms  of  the  sounds,  the  word- hearing 
center  is  the  seat  of  the  nerve  activity;  if  you  form  the  words 
in  your  throat,  the  nerve  activity  is  in  the  word-uttering 


CH.  xin]  KINDS  OF  THOUGHT  295 

center.  In  the  vocal  type  of  thinking,  the  thought  is  usually 
not  expressed  aloud;  there  is  merely  a  slight  muscular  adjust- 
ment which  is  not  detected  except  by  very  delicate  instru- 
ments.* Individuals  of  the  'visual'  tyi>e,  who  think  in 
terms  of  the  looks  of  printed  words,  use  the  reading  center  in 
thinking.  The  destruction  of  any  one  of  the  four  special 
centers  leads  to  disturbances  of  thought  as  well  as  of  lan- 
guage. This  is  why  aphasic  patients  of  certain  types  often 
break  off  in  a  sentence  and  seem  to  lose  track  of  their  thoughts. 

Meaning  and  Value.  —  Although  thoughts  are  symbols, 
every  thought  contains  certain  elements  which  resemble  the 
object  or  situation  we  are  thinking  about.  These  "  bits  of  the 
real  thing  "  make  up  the  meaning  of  the  thought.  When  we 
think  of  man,  the  arbitrary  word  '  man  '  is  the  central  feature 
or  focus  of  the  experience.  But  at  the  same  time  there  is 
somewhere  in  the  background  or  margin  of  the  thought  a 
fleeting  image  of  some  particular  man  or  of  certain  human 
characteristics.  These  faint  images  constitute  the  meaning. 
In  other  words,  the  meaning  of  a  thought  comprises  those 
elements  in  the  experience  which  correspond  to  the  object  or 
situation,  as  distinguished  from  the  mere  verbal  or  symbolic 
elements.  When  you  try  to  examine  the  meaning  of  a  word, 
by  observing  it  closely,  what  happens  is  that  these  marginal 
elements  become  prominent.  This  occurs  very  notably  in 
scientific  and  logical  thinking,  where  the  meaning  is  especially 
important.     On  the  other  hand,  if  you  take  a  famiUar  word 

and  repeat  it  over  and  over  again  (man-man-man-man ) 

it  finally  loses  all  meaning:  the  sound  becomes  so  insistent 
that  the  image  elements  disappear  altogether. 

The  value  experience  is  the  same  sort  of  thing  as  the  experi- 
ence of  meaning,  except  that  it  has  to  do  with  intensity  and 
quantity.  Your  thought  of  a  book  is  usually  tinged  with 
some  idea  of  its  being  thick,  long,  heavy,  difficult  to  read, 
true  —  or  the  opposite  of  these.  In  most  cases  these  ideas 
^  These  slight  vocal  adjustments  are  called  implicit  responses. 


296  LANGUAGE  AND  THOUGHT         [ch.  xiii 

are  vague  and  only  form  part  of  the  margin  of  the  thought. 
They  make  up  its  value  tinge.  But  if  we  attend  closely  to 
some  quantitative  characteristic  of  an  object,  this  value  ele- 
ment comes  to  the  foreground;  we  get  a  rather  new  sort  of 
experience  —  the  idea  of  value.  The  value  idea  is  especially 
prominent  in  sentiments  (ch.  ix) ;  a  belief  is  partly  an  idea  of 
the  worth  of  some  statement,  partly  a  feeling. 

The  same  experience  may  have  very  different  values 
attached  to  it  at  different  times.  When  Newton  saw  the 
apple  fall,  it  probably  seemed  a  trivial  occurrence.  After- 
wards, as  he  thought  about  it  more  carefully  and  formulated 
the  law  of  gravitation,  the  experience  acquired  a  meaning 
and  a  value  hitherto  undreamed  of. 

Psychology  investigates  the  nature  of  our  experience  of 
value,  but  it  has  nothing  to  do  with  finding  out  the  real  value 
of  things.  Logic  determines  what  is  true;  esthetics  shows 
what  is  beautiful;  ethics  teaches  what  is  good.  These 
sciences  enable  us  to  adjust  our  valuation  of  situations  and 
events  to  the  *  objective  values  '  of  the  world  about  us.  One 
might  almost  regard  them  as  instances  of  applied  psychology. 

This  distinction  brings  out  an  interesting  peculiarity  of  the 
psychologist's  attitude  toward  social  relations.  Psychology 
is  just  as  much  concerned  with  faulty  logic  and  bad  conduct 
as  with  their  opposites.  The  psychologist  knows  that  in 
each  case  the  error  is  due  to  something  in  the  man's  nature. 
He  does  not  approve  of  immorality,  but  he  treats  it  as  a  fact 
to  be  studied  carefully  and  dispassionately.  When  he  comes 
across  an  instance  of  wrong-doing  he  does  not  proceed  at  once 
to  reprove  or  punish;  his  first  duty  is  to  determine  where  the 
trouble  lies.  Often  this  suggests  a  remedy  which  avoids  the 
need  of  punishment.  A  child  may  lie  because  he  does  not 
appreciate  the  distinction  between  memory  and  imagination; 
he  may  be  disobedient  because  his  attention  has  not  been 
trained  to  listen  to  what  you  tell  him;  he  may  be  quarrelsome 
or  obstreperous  on  account  of  digestive  disorders.     In  short, 


CH.  xra]  MEANING  AND  VALUE  297 

it  is  the  business  of  the  psychologist  to  try  first  of  all  to 
understand  the  situation  which  led  to  these  breaches  of  ethics. 
The  practical  result  of  this  attitude  is  seen  in  the  recent  im- 
provement of  the  methods  of  handling  delinquents  and 
criminals,  which  is  attributable  in  no  small  degree  to  the 
work  of  psychologists. 
1^  Rational  Thought  and  Rational  Behavior.  —  As  human 
^  thinking  progresses,  the  meaning  and  value  elements  in 
thought  become  more  prominent  and  at  the  same  time  the 
meaning  of  familiar  words  tends  to  become  stereotyped. 
When  you  think  of  a  horse,  the  meaning  of  your  thought 
includes  certain  definite  characteristics  common  to  all  horses. 
When  you  try  to  make  your  thought  correspond  as  nearly  as 
possible  to  what  horses  really  are,  the  more  trivial  associations 
fade  away;  only  those  remain  which  are  characteristic  or  sig- 
nificant. In  the  same  way  the  value  elements  in  your 
thoughts  tend  to  conform  to  the  real  values  of  the  objects.  A 
horse  is  larger  than  a  man,  smaller  than  an  elephant.  A 
thought  which  includes,  besides  the  word,  only  the  reaVLy 
characteristic  elements  of  meaning  or  value,  is  called  a  concept. 
A  concept  is  a  special  type  of  thought  which  tends  to  be  "  true 
to  life." 

A  judgment  is  a  thought  which  combines  two  concepts.  If 
we  combine  the  concept  of  a  horse  with  the  concept  of  a 
vertebrate,  we  obtain  the  judgment,  "  Horse  —  vertebrate," 
—  or,  as  it  is  expressed  in  language,  "  A  horse  is  a  vertebrate," 
or,  "  All  horses  are  vertebrates."  When  we  think  of  a  certain 
light  and  of  its  intensity,  and  combine  the  meaning  with  the 
value,  the  resulting  thought  is  the  judgment,  "  This  light  is 
bright." 

Concepts  and  judgments  are  rational  thoughts.  They  are 
distinguished  from  ordinary  thoughts  by  their  greater  pre- 
cision and  by  their  close  correspondence  with  real  things. 
Our  ordinary  thoughts  grow  up  in  haphazard  fashion.  They 
contain  irrelevant  elements  tacked  on  from  casual  associa- 


298  LANGUAGE  AND  THOUGHT        [ch.  xiii 

tions.  Your  casual  thought  of  a  harbor  may  be  associated 
with  docks  and  your  thought  of  a  lake  with  islands.  Neither 
of  these  associations  is  characteristic.  As  your  experience 
broadens  they  fade  away;  your  concept  (rational  thought)  of  a 
harbor  does  not  include  docks,  and  your  concept  of  a  lake  does 
not  include  islands. 

Since  thought  is  closely  bound  up  with  language,  rational 
thought  has  led  to  special  sorts  of  verbal  expression.  The 
language  equivalent  of  a  concept  is  a  term;  the  equivalent  of 
a  judgment  is  a  'proposition.  The  judgment '  horse  —  black  ' 
may  be  instantaneous,  but  the  proposition  takes  time;  it 
starts  with  one  term  and  the  other  term  comes  afterwards. 
This  involves  a  succession  of  experiences  (ch.  xiv). 

Rational  thought  assists  us  tremendously  in  handling  real 
situations.  Pure  fancy,  as  aroused  by  fairy-tales  for  instance, 
is  a  source  of  enjoyment  in  our  leisure  hours;  but  it  does  not 
help  us  to  meet  the  problems  of  real  life.  The  more  closely  our 
thoughts  correspond  to  actual  situations  in  the  world  about 
us,  the  more  appropriate  our  responses  are  likely  to  be. 
Behavior  based  on  rational  thought  is  rational  behavior,  which 
is  a  stage  higher  than  ordinary  intelligent  behavior.  Any 
action  that  is  brought  about  by  individual  acquisition  is 
intelligent  behavior;  an  action  is  rational  only  if  it  is  brought 
about  by  rational  thought.  The  higher  animals  act  intelli- 
gently, but  they  do  not  act  rationally,  because  their  behavior 
is  not  guided  by  thought.  A  human  child  begins  to  act 
rationally  as  soon  as  he  acquires  thoughts  with  definite  mean- 
ings. Rational  thought  and  rational  behavior  are  often 
called  reason. 

The  popular  notion  of  reason  is  wrong  in  making  it  a  special 
faculty  of  the  human  mind.  It  is  not  a  brand-new  mental 
endowment,  but  an  outgrowth  of  more  fundamental  experi- 
ences. Mental  development  is  one  single  continuous  process 
from  the  simplest  type  of  stimulation  and  response  to  ra- 
tional behavior.     There  is  no  break,  no  sudden  jump. 


CH.  xm]  RATIONAL  THOUGHT  299 

There  is  also  a  popular  notion  that  human  reason  is  infalli- 
ble. As  a  matter  of  fact  it  is  quite  liable  to  make  mistakes. 
Our  direct  information  concerning  the  world  is  obtained 
through  our  senses.  This  information  is  put  together  (inte- 
grated) by  combining  sensations  into  perceptions,  memories, 
and  thoughts.  Any  misinformation  may  be  corrected  even 
apart  from  reason  by  cutting  out  chance  associations  and 
broadening  our  outlook  on  the  world.  Rational  thought  is 
merely  the  final  focusing  of  the  picture. 

On  the  other  hand,  if  our  perceptions  are  wrong,  even 
reason  may  be  unable  to  correct  the  impression.  In  ancient 
times  the  most  rational  concept  of  the  earth  was  of  a  flat,  solid 
body,  surmounted  by  a  transparent  dome,  in  which  the  stars 
were  fixed.  The  rational  judgment  of  matter  was  that  it  con- 
sisted of  four  elements  —  earth,  air,  fire,  and  water.  Many 
of  the  rational  thoughts  of  antiquity  have  been  found  not  to 
correspond  to  actual  conditions;  —  and  many  concepts  and 
judgments  accepted  to-day  are  doubtless  just  as  false.  Ra- 
tional thought  furnishes  merely  our  nearest  approach  to  the 
truth. 

Importance  of  Language  and  Thought.  —  It  is  scarcely  pos- 
sible to  exaggerate  the  importance  of  language  and  thought 
in  the  mental  life  of  man.  They  lead  to  two  new  kinds  of 
behavior,  communication  and  rational  behavior,  which  carry  us 
to  a  higher  stage  of  mental  life  than  the  trial-and-error  way  of 
learning.  Taken  together,  language  and  thought  provide  a 
tremendously  effective  means  for  adapting  our  responses  to 
the  general  conditions  of  the  environment. 

More  than  any  other  type  of  experience,  except  perhaps 
emotion,  language  and  thought  must  be  studied  in  the  hght 
of  their  history.  But  emotion  is  a  survival  from  ancestral 
conditions,  while  language  and  thought  are  recent  human 
acquisitions.    They  are  still  in  the  making  —  still  improving. 

A  noticeable  feature  in  the  growth  of  language  is  its  slow 
evolution  in  the  race  and  its  rapid  development  in  the  indi- 


300  LANGUAGE  AND  THOUGHT        [ch.  xiii 

vidual.  New  words  are  invented  gradually,  as  the  sphere  of 
thought  in  the  race  enlarges.  Once  adopted  they  are  trans- 
mitted rapidly  to  the  bulk  of  individuals  in  the  community; 
each  child  acquires  a  large  vocabulary  at  an  early  age. 

Much  the  same  is  true  in  regard  to  thought.  The  growth  of 
thought  depends  upon  the  existence  of  words.  If  the  vocabu- 
lary of  a  community  is  scanty,  the  range  of  thought  is  limited. 
Given  a  rich  vocabulary,  the  mentally  well-developed  indi- 
viduals in  the  community  quickly  attain  a  wide  range  of 
thought. 

The  development  of  language  and  thought  in  the  individual 
depends  not  only  upon  the  social  environment,  but  upon 
inherited  nerve  structure.  In  order  to  speak  (to  use  vocal 
language)  we  must  possess  inherited  pathways  between  the 
word-hearing  center  and  the  word-uttering  center.  Writing 
involves  countless  pathways  between  the  word-seeing  or 
word-hearing  center  and  the  word-writing  center.  It  is 
because  of  the  great  masses  of  association  fibers  present  from 
birth  in  the  human  cortex,  that  man's  intellect  is  so  vastly 
superior  to  that  of  any  other  species.  Within  the  human 
species  it  is  the  sphere  of  thought,  more  than  any  other  de- 
partment of  mental  life,  that  reveals  the  greatest  individual 
diflFerences  in  capacity  and  attainment.  This  is  especially 
true  of  rational  thought. 

Training  of  Thought  and  Language.  —  The  highest  stage  of 
general  education  is  largely  a  training  of  thought  and  of  the 
rational  processes  that  grow  out  of  it.  If  primary  education 
teaches  us  to  perceive,  and  secondary  education  teaches  us  to 
remember,  college  education  should  teach  us  to  think.  This 
special  objective  is  often  overlooked  by  both  instructor  and 
student.  Too  much  emphasis  is  laid  on  imparting  mere  facts, 
and  on  retaining  them  —  till  after  the  final  examination.  It 
is  far  more  useful  to  know  how  to  think  about  the  facts,  —  to 
understand  the  principles  of  whatever  branch  we  are  study- 
ing.   You  can  readily  find  the  value  of  the  gravity  factor  g  in 


CH.  xiii]  TRAINING  OF  THOUGHT  301 

your  physics  book.  It  is  more  useful  to  understand  such 
principles  as  the  elliptical  motion  of  planets.  In  psychology 
it  is  much  more  important  to  get  the  right  notion  about  the 

*  learning  process  '  than  to  memorize  any  of  the  tables  or 
definitions  in  this  book. 

The  training  of  thought  means  especially  the  cultivation  of 
rational  thought  —  of  clear  thinking,  as  it  might  be  called. 
The  best  way  to  accomplish  this  is  to  ponder;  —  not  to  memo- 
rize, in  an  effort  to  retain,  but  to  seek  out  the  connections 
between  the  facts.  Try  to  picture  the  relations  step  by  step. 
Practice  makes  the  process  continually  easier. 

A  practical  problem  in  education  is  whether  to  cultivate 

*  visual  *  or  *  auditory  '  thinking.  Some  students  master  a 
subject  better  by  reading,  and  others  by  listening  to  lectures. 
(So-called  mental  arithmetic  is  really  auditory  arithmetic.) 
Both  methods  should  be  cultivated,  because  both  methods  of 
imparting  knowledge  are  constantly  used  in  modern  educa- 
tion. Text-books  give  the  main  principles;  the  diflSculties 
that  strike  any  individual  student  are  better  overcome  by 
word  of  mouth.  An  important  point  is  to  learn  to  suppress 
the  motor  type  of  thinking.  You  will  read  more  quickly  — 
and  understand  quite  as  well  —  if  you  learn  to  suppress  the 
incipient  tendencies  to  utter  the  words  or  to  form  them  with 
the  lips  and  throat.  Such  motor  accompaniments  act  as  a 
drag  in  reading,  and  they  rarely  make  the  thought  more  clear. 
Their  only  real  use  is  to  focus  your  wandering  attention  when 
you  are  tired  or  the  subject  is  uninteresting. 

Psychology  is  not  especially  concerned  with  vocal  enuncia- 
tion, except  that  stuttering  and  faulty  pronunciation  often 
indicate  faulty  coordination  in  the  brain  centers.  Psychol- 
ogy is  more  interested  in  diction.  Certain  types  of  sentence, 
the  use  of  certain  words,  indicate  clear  thinking.  Faulty 
grammatical  construction  and  the  use  of  incorrect  words  or 
vague  phrases  indicate  slovenly  habits  of  thought.  It  is 
often  a  help  to  the  student  for  the  teacher  to  ask,  "  What  do 


302  LANGUAGE  AND  THOUGHT        [ch.  xiii 

you  mean  by  this  sentence  (or  word)?"  The  very  challenge 
may  lead  to  clearer  conception. 

An  important  problem  in  education  is  to  teach  the  child  to 
maintain  a  proper  balance  between  language  and  thought. 
The  contemplative,  silent  man  overemphasizes  the  thought 
side  and  is  inclined  to  be  unsociable.  The  voluble  man 
dresses  his  thoughts  in  public,  instead  of  within  the  private 
chambers  of  his  own  mind.  It  is  the  task  of  the  educator  to 
subdue  the  chatterer  and  draw  out  the  reticent  one.  To  suc- 
cessfully attain  a  happy  mean,  this  training  must  be  begun 
early  in  life. 

Higher  and  Lower  Levels  of  Behavior.  —  Language  and 
thought,  as  we  have  seen,  involve  a  higher  sort  of  behavior 
than  other  types  of  experience.  Their  relation  to  the  two 
lower  levels  of  mental  life  is  shown  in  the  accompanying 
diagram.     [Fig.  78.] 

(1)  Lowest  Nervous  Abc:  From  the  various  receptors  the 
sensory  nerves  lead  first  of  all  to  the  primary  centers.  There 
are  numerous  primary  centers  in  the  cord  and  in  the  lower 
part  of  the  brain;  but  in  the  diagram,  for  simplicity,  they  are 
grouped  into  three  headings :  external,  systemic,  and  motor- 
sense  centers.  From  these  primary  sensory  centers  the  nerve 
impulse  may  pass  over  directly  into  one  of  the  primary  motor 
centers  (shown  at  the  right  of  the  figure),  and  from  there 
pass  down  directly  to  some  muscle  or  gland  or  over  into  the 
autonomic  system.  This  lowest  nervous  arc  gives  reflex 
actions,  the  simplest  type  of  behavior. 

(2)  Intermediate  Nervous  Arc:  From  the  primary  sen-, 
sory  centers,  paths  lead  up  to  the  cortex,  and  to  the  various 
centers  there.  These  secondary  or  intermediate  centers  are 
active  in  our  experiences  of  perception  and  imagery,  feeling, 
emotion,  and  volition.  They  are  closely  interconnected,  so 
that  a  whole  chain  of  experiences  may  succeed  one  another 
before  any  important  motor  impulse  is  started  (ch.  xiv). 
But  sooner  or  later  the  nerve  impulse  passes  over  to  some 


CH.  xin 


LEVELS  OF  BEHAVIOR 


303 


secondary  motor  center,  and  from  there  an  outbound  impulse 
goes  out  to  the  lower  motor  centers  and  thence  to  the  effect- 


Vferbal    and 

Rational 
Molor  Ccrflers 


3*  ARC 

CommunicAlan 

Rational  AcUon 


Reccfton 
{Sense 


EffWtors 
(Motor 
Oraans) 


Cxieroceptors    IriltrxKtfUon    Prophocefftors 

Fig.  78.  —  Mextal  Levels 


Diagram  showing  the  three  levels  of  nervous  arcs  and  the  grade  of  mental  life  corresponding 
to  each  level.  Arrows  indicate  direction  of  nerve  current.  Broken  lines  (below  at  right)  indi- 
cate that  motor  expression  stimulates  muscle  sensations.  The  centers  are  shown  very  sche- 
matically; e.g.,  many  separate  centers  are  included  in  square  labeled  "external  sense  centers." 

ore.    The  movements  resulting  from  these  second-level  motor 
impulses  are  coordinated;  they  differ  in  this  respect  from 


304       LANGUAGE  AND  THOUGHT   [ch.  xin 

simple  reflexes.  The  operation  of  the  secondary  nervous  arc 
gives  instinctive  and  intelligent  behavior  —  usually  a  combi- 
nation of  the  two. 

(3)  Highest  Nervous  Arc  :  In  man  a  third  set  of  centers 
and  a  tertiary  nervous  arc  have  developed.  Impulses  from 
the  second-level  experience  centers,  instead  of  going  over  to 
the  motor  centers  directly,  may  pass  up  to  the  centers  for 
thought  and  language.  From  these  centers  the  nerve  im- 
pulse passes  over  into  the  verbal  and  rational  motor  centers 
and  then  down  through  motor  paths  to  the  lower  motor 
centers  and  out  to  the  effectors.  This  highest  level  of  be- 
havior has  two  different  forms:  communicqjiDn  and  rational 
actigiiit^ 

The  development  of  the  two  higher  levels  of  the  nervous  arc 
is  accompanied  by  more  perfect  adjustment  of  the  responses. 
The  behavior  is  more  controlled,  and  more  suited  to  the 
*  entire  situation'  than  the  simple  reflexes.  Rational  behav- 
ior is  much  more  adaptive  and  controlled  than  ordinary 
intelligent  or  instinctive  behavior. 

Summary.  —  In  chapters  vii  to  xiii  we  have  examined  the 
various  kinds  of  experiences  which  are  found  in  man.  Per- 
ception, memory,  and  imagination  are  built  out  of  sensations 
which  we  receive  from  the  world  around  us;  feelings  come  from 
systemic  sensations;  and  conations  from  motor  sensations. 
There  are  also  experiences  derived  from  two  sources:  emo- 
tions are  built  up  out  of  systemic  and  motor  sensations, 
sentiments  out  of  systemic  sensations  and  ideas,  volitions 
out  of  motor  sensations  and  ideas.  There  are  also  experi- 
ences called  ideals,  which  are  derived  from  all  three  sources. 

The  highest  types  of  human  experience  are  language  and 
thought,  which  are  brought  about  by  a  third  level  of  nervous 
arc  and  involve  four  special  centers  in  the  brain. 

All  these  kinds  of  experience  are  different  ways  of  putting 
together  (integrating)  the  information  brought  in  over  the 
sensory  nerves.    Their  real  significance  in  psychology  is  their 


CH.  xiii]  SUMMARY  305 

relation  to  behavior.  Our  responses  are  more  suitable  accord- 
ing as  the  stimuli  are  more  completely  integrated  —  that  is, 
as  our  sensations  are  organized  into  definite  experiences. 

Practical  Exercises: 

64.  What  constitutes  your  thought  of  school,  idiot,  orchestra,  Egypt, 
steamboat,  thunder-storm,  medicine,  penitence? 

65.  Ask  some  one  to  read  aloud,  and  at  the  same  time  to  think  of  other 
things;  note  how  far  the  distraction  interferes  with  his  pronunciation 
and  especially  with  the  vocal  inflections  which  "give  the  sense." 

66.  Take  two  similar  problems  in  physics,  geometry,  or  some  other 
science.  Read  one  to  yourself  and  have  a  friend  read  the  other  aloud 
to  you.  Compare  your  experiences  in  "understanding  the  problem" 
by  the  two  methods. 

67.  Ask  some  one  to  prepare  a  typewritten  page  with  many  typographical 
errors.  Read  the  page  rapidly,  checking  the  errors  noticed.  Read 
again  carefully  and  observe  what  mistakes  have  escaped  you.  Do  you 
notice  errors  better  if  they  look  like  the  right  word  but  sound  different 
(e.g.  though  and  thought)  or  if  they  sound  like  the  right  word  and 
look  different  (e.g.  right  and  write) .' 

68.  Observe  the  speech  of  a  two  or  three  year  old  child.  Report  any  not- 
able mistakes  in  pronunciation,  grammar,  misuse  of  words,  and  sug- 
gest the  explanation  of  these  errors. 

References: 
On  language:  C.  H.  Judd,  Psychology,  rev.  ed.,  ch.  10;  J.  London,  Before 

Adam,  ch.  4. 
On  writing:  J.  E.  Downey,  Graphology  and  the  Psychology  of  Handwriting. 
On  relation  of  language  to  thought:  G.  F.  Stout,  Analytic  Psychology, 

ch.  10;  Max  MUller,  Science  of  Thought. 
On  meaning  and  value:  W.  M.  Urban,  Valuation,  chs.  2-5. 


CHAPTER  XIV 

MENTAL  SUCCESSION 

The  Stream  of  Consciousness.  —  Thus  far  we  have  consid- 
ered detached,  isolated  experiences  and  responses.  But  this 
is  only  part  of  the  story.  In  reality  our  states  of  mind  are  not 
completely  separated  from  one  another.  Mental  life  is  not  a 
series  of  independent  happenings.  Each  experience  and  each 
act  is  affected  by  our  past  experiences  and  actions. 

Human  actions  are  rarely  instantaneous.  The  response  to 
a  given  situation  often  involves  a  long  series  of  actions,  one 
step  leading  to  the  next.  If  one  step  is  cut  out  or  if  the  order 
of  procedure  is  inverted,  the  action  may  be  quite  ineffective 
and  even  absurd.  You  must  load  your  gun  before  you  press 
the  trigger,  and  thread  your  needle  before  you  begin  to  sew. 
For  the  most  part  behavior  is  a  continuous  process,  not  a  series 
of  detached  reflexes.    Each  step  passes  gradually  into  the  next. 

Our  mental  life,  with  its  various  experiences  and  actions, 
may  be  likened  to  a  stream  which  flows  steadily  onward, 
moment  by  moment,  day  by  day,  year  by  year,  bearing  on 
its  bosom  ships  and  cargoes  of  various  sorts.  We  often  speak 
of  the  '  flow  of  thought '  and  the  *  flow  of  language.'  It  is  not 
so  common  to  speak  of  the  flow  of  perceptions  or  feelings,  but 
these  and  all  other  experiences  flow  along  in  much  the  same 
way.  James  calls  this  general  flow  of  experiences  the  stream 
of  consciousness.  Our  conscious  life  at  any  instant  is  a  cross- 
section  of  the  stream.  The  present  cannot  be  fully  under- 
stood except  by  reference  to  what  has  gone  before.  Under- 
lying the  thoughts  and  perceptions  of  conscious  life  is  the 
stream  of  nerve  impulses  which  course  through  the  brain,  rous- 
ing now  one  experience,  now  another,  in  endless  succession. 

The  simile  of  the  stream  helps  us  to  picture  the  '  flow ' 


CH.  XIV]       STREAM  OF  CONSCIOUSNESS  307 

of  life.  In  other  respects  it  is  imperfect.  Our  experiences 
are  not  uniform  like  a  stream  of  water.  Perceptions  are  quite 
different  from  thoughts;  and  these  two  types  of  experience 
flow  along  in  very  different  ways.  The  flow  of  perceptions  is 
controlled  largely  by  the  succession  of  stimuli  that  happen  to 
affect  us,  while  the  flow  of  thoughts,  memories,  and  images  is 
determined  almost  wholly  by  conditions  in  the  brain.  There 
are  really  two  different  currents  in  our  mental  life,  or  (better) 
two  separate  strands  which  interweave  to  form  the  texture  of 
experience. 

Speed  of  Thought;  Reaction  Time.  —  How  rapidly  do  our 
experiences  flow?  Popular  notions  on  this  point  are  quite 
vague.  Fanciful  stories  are  told  of  drowning  men  who  live 
over  their  entire  lives  in  a  few  minutes.  We  hear  of  dreams 
which  involve  a  long  succession  of  events  lasting  a  year  or 
more,  ending  with  the  crashing  of  a  real  mirror  which  wakens 
the  sleeper  —  the  whole  dream  having  presumably  been 
started  by  the  crash  itself.  Such  stories  lead  to  wrong  ideas 
of  the  duration  of  our  experiences.  The  terror  of  drowning 
may  arouse  many  memories  which  had  lain  dormant  for 
years,  and  may  speed  up  the  flow  of  thought  considerably, 
but  there  is  a  limit  to  the  speeding-up  process.  In  the  mirror 
dream  the  experiences  probably  came  in  the  form  of  an 
instantaneous  picture;  the  background  of  the  picture  was  an 
illusory  memory,  in  which  the  dreamer  seemed  to  have  lived 
over  the  events  successively.  There  is  undoubtedly  a  slip 
somewhere  in  all  such  stories  —  either  an  exaggeration  of  the 
number  of  experiences  involved  or  a  wrong  interpretation  of 
the  experience  itself. 

The  rate  of  change  in  p>erceptions  and  thoughts  is  limited 
by  the  rate  of  conduction  of  the  nerve  impulse.  The  highest 
velocity  of  nerve  impulse  so  far  discovered  by  physiological 
experiment  is  about  400  feet  per  second.  The  resistance  at 
the  synapses  causes  delay,  and  this  lengthens  the  time  of 
passage  from  neuron  to  neuron. 


308  MENTAL  SUCCESSION  [ch.  xiv 

Having  found  this  physiological  limit,  the  next  step  is  to 
determine  in  how  short  a  time  a  simple  mental  act  can  be 
accomplished.  This  has  been  determined  by  experiments  in 
the  laboratory.  A  stimulus  is  given  —  a  sudden  flash  of  light 
or  a  noise;  as  soon  as  the  subject  perceives  it  he  presses  a  key. 
By  means  of  electrical  connections  the  stimulus  starts  the 
hands  of  a  chronoscope  [Fig.  79],  and  the  pressure  of  the  keys 
stops  them,  so  that  the  duration  of  the  entire  stimulus- 
response  process  is  accurately  measured.  This  duration  is 
called  reaction  time.  If  the  subject  has  been  trained  to  react 
to  the  stimulus  as  quickly  as  possible,  the  reaction  time  repre- 
sents his  utmost  speed  for  this  particular  kind  of  perception. 

Reaction  time  is  divided  into  three  periods:  (1)  Sensory 
conduction  from  the  receptor  to  the  brain  center.  (In  this 
period  is  included  the  time  required  for  the  stimulus  to  excite 
the  receptor  and  sensory  nerve.)  (2)  Central  processes.  In 
simple  reactions  this  period  is  devoted  to  the  mental  process 
of  perceiving;  but  in  complicated  experiments  certain  other 
central  processes,  such  as  discrimination  or  association,  take 
place  before  the  motor  impulse  starts.  (3)  Motor  conduction 
of  the  nerve  impulse  from  the  brain  to  the  muscle,  together 
with  the  time  needed  for  the  muscular  contraction  to  take 
place. 

Although  the  rate  of  nerve  conduction  is  approximately 
known,  the  duration  of  the  two  conduction  periods  is  not 
completely  determined,  because  we  do  not  know  how  much 
time  is  required  for  the  impulse  to  pass  through  the  synapses 
nor  the  length  of  the  reception  and  muscular-contraction 
periods.  Visual  reaction,  for  example,  is  found  to  be  consid- 
erably longer  than  auditory  or  tactile  reaction,  probably 
because  the  eye  takes  longer  to  receive  its  stimulus  than  the 
ear  or  the  touch  corpuscles.  There  is  also  found  to  be  con- 
siderable difference  in  the  reaction  times  of  the  same  person 
according  as  his  attention  is  fixed  on  the  stimulus  (sensory 
reaction)  or  upon  the  movement  (muscular  reaction).    While 


FiQ.  79.  —  Hipp  Chronoscope 


Instrument  used  for  measuring  reaction  lime.  Each  dial  is  divided  into  100  units.  Upper 
dia]  measures  thousandths  of  a  second  (0.001  second  =  1  sigma);  lower  dial  measures 
tenths  of  a  second.  Clock-work  (behind  the  dials)  is  started  and  stopped  by  pulling  the 
cords  \,  A'  at  left;  hands  do  not  move  till  an  electric  current  meshes  a  cogwheel  (back  of 
upper  dial)  into  the  clock-work.  The  wires  of  the  circuit  are  joined  with  the  Hipp  at  bind- 
ing posts  B,  B'.  Circuit  is  made  when  the  stimulus  is  given,  and  broken  when  the  subject 
reacts  by  pressing  a  key.  Weight  C  furnishes  motor  power  for  clockwork;  the  speed  is  gov- 
erned by  vibrations  of  a  small  reed  D,  which  vibrates  over  a  cogwheel. 


810  MENTAL  SUCCESSION  [ch.  xiv 

there  is  considerable  variation  between  the  reaction  times  of 
different  individuals,  the  figures  given  in  Table  XIII  repre- 
sent the  average  perceptual  reactions  of  trained  subjects. 
The  unit  of  measurement  is  the  thousandth  part  of  a  second, 
which  is  called  a  sigma  (o-). 

Table  XIII. —  Reaction  Time  of  Perception 
Stimulus  Sensory  Attention  Muscular  Attention 

Light  290(7  180<r 

Sound  225  120 

Electric  on  skin  210  105 

[From  Titchener,  Text-book,  p.  432.] 

If  the  observer  is  directed  to  perform  some  mental  act  in 
addition  to  perception  before  he  presses  the  key,  the  experi- 
ment measures  complex  reaction  time.  The  experimenter  may 
show  in  turn  a  number  of  different  colors  in  chance  order,  and 
require  the  subject  to  recognize  the  color  before  pressing  the 
key.  Or  the  subject  is  required  to  press  one  key  for  blue, 
another  for  red,  and  so  on.  This  is  discrimination  reaction 
time.  In  any  complex  reaction  the  conduction  time  to  and 
from  the  center  is  the  same  as  in  perception  reaction,  so  that 
the  increased  duration  of  the  reaction  represents  the  time 
required  for  the  additional  mental  process. 

Titchener  found  in  his  own  case  that  recognition  of  a  color 
required  280"  longer  than  simple  visual  reaction.  His  recog- 
nition time  for  a  letter  of  the  alphabet  was  51  a  and  for  a  short 
word  45<r.  These  relations  hold  generally,  though  the  abso- 
lute times  vary  for  different  persons;  it  requires  less  time  to 
recognize  a  word  of  three  letters  than  a  single  letter. 

Experiments  have  been  made  on  the  time  required  to 
associate  one  thought  with  another.  The  stimulus  is  a 
printed  or  spoken  word.  When  the  observer  sees  or  hears  the 
word  it  arouses  a  thought  in  his  mind;  he  is  directed  to  react 
just  as  soon  as  this  thought  suggests  another  idea.  The 
experiment  may  be  safeguarded  by  having  the  observer  react 
by  speaking  the  word  aloud  instead  of  pressing  a  key;  the 


CH.  xiv]  REACTION  TIME  311 

voice  strikes  a  sensitive  membrane,  whose  vibrations  press  a 
small  hammer  so  that  it  makes  the  electric  contact.  In  a 
series  of  over  6000  auditory  association  reactions  on  22  per- 
sons Wreschner  found  that  the  average  association  reaction 
time  was  about  2000(r  (2  seconds). 

The  experimental  investigation  of  reaction  time  has  not 
fully  solved  the  problem  of  the  rate  at  which  our  experiences 
follow  one  another.  Slight  changes  in  perceptions  may  take 
place  much  more  rapidly  than  the  rise  of  new  perceptions; 
thoughts  may  be  modified  in  some  of  their  details  more 
quickly  than  a  brand-new  association  can  be  formed.  But 
just  as  light  has  a  limiting  rate  of  transmission,  so  we  are 
certain  that  thought  and  perception  have  their  speed  limit. 
'Quick  as  lightning'  does  not  mean  'instantaneously'; 
neither  does  '  quick  as  thought.' 

The  Stream  of  Perceptions.  —  A  large  portion  of  our  expe- 
riences are  the  direct  result  of  stimuli  outside  our  body. 
These  stimuli  are  changing  constantly,  and  give  rise  to  a 
stream  of  perceptions.  Our  mental  life  often  consists  for  a  long 
time  of  a  series  of  perceptions,  uninterrupted  by  any  notable 
experiences  of  other  sorts.  We  may  see,  hear,  *  palp,'  and 
*  heft '  the  things  about  us  without  being  affected  by  any 
striking  emotion,  and  without  having  any  definite  thoughts 
or  memory  pictures. 

The  succession  of  these  experiences  depends  primarily  upon 
conditions  in  the  environment.  Stimuli  which  affect  our 
eyes,  ears,  skin,  and  nostrils  are  due  mainly  to  forces  out- 
side our  own  body,  which  are  for  the  most  part  independent 
of  our  will.  We  do  not  control  the  flow  of  perceptions  in  the 
same  way  that  we  control  our  own  movements,  feelings,  and 
ideas. 

I  can  readily  arouse  a  thought  of  my  brother;  but  I  cannot 
arouse  a  perception  of  him  if  he  happens  to  be  a  hundred  miles 
away.  You  can  arouse  the  memory  of  a  rose  and  the  feeling 
of  pleasure  at  its  form  and  odor;  but  you  cannot  get  a  per- 


312  MENTAL  SUCCESSION  [ch.  xiv 

ception  of  its  form  or  a  sensation  of  its  odor  if  there  is  no  rose 
present  to  stimulate  your  eyes  and  nostrils. 

Our  ability  to  control  our  perceptions  is  mostly  by  way  of 
prevention  —  not  production.  We  can  reduce  a  perception 
to  the  margin  of  consciousness  by  attending  to  something 
else;  we  may  get  rid  of  it  entirely  by  closing  the  eyes  or  walk- 
ing away.  Often  we  modify  a  perception  by  adding  images  or 
thoughts,  so  that  a  tree  seen  in  the  dusk  becomes  a  bird  or 
camel.  But  we  have  little  power  to  produce  any  desired  per- 
ception at  will.  The  ultimate  source  of  perception  lies  in  the 
world  outside  us. 

The  succession  of  perceptions  is  determined  by  the  follow- 
ing factors : 

(1)  External  stimuli  and  their  changes. 

(2)  The  manner  of  stimulation.  We  see  an  object  differ- 
ently according  as  we  look  at  it  with  the  center  of  the  eye  or 
the  periphery. 

(3)  Retention  of  the  effect  of  similar  stimuli  that  occurred 
in  the  past.  Repetition  and  retention  improve  one's  ability 
to  pick  out  certain  stimuli  and  combine  them  into  perceptual 

y^    states. 

(4)  Systemic  and  motor  stimuli  which  occur  at  the  time. 
Excitement,  pain,  distaste,  pleasure,  may  inhibit  certain 
perceptions  and  emphasize  others.  Motor  stimuli  and  the 
resulting  motor  activity  enable  us  to  get  rid  of  certain  ex- 
ternal stimuli  and  substitute  others. 

Of  these  four  factors  all  but  the  first  are  conditions  within 
our  own  body.  Yet  the  external  factor  is  the  great  determin- 
ing condition  of  perception  and  outweighs  in  importance  all 
the  others  combined.. 

The  Stream  of  Thought.  —  The  mental  life  of  civilized  man 
often  includes  a  long  succession  of  memories,  images,  and 
^'  thoughts  uninterrupted  by  perceptions.  The  starting-point 
of  such  a  series  is  always  a  perception  or  some  other  sensory 
experience;  but  the  train  of  ideas,  once  started,  may  proceed 
for  a  long  time  without  interference. 


CH.  xiv]  STREAM  OF  THOUGHTS  813 

In  subhuman  species  prolonged  trains  of  ideas  apparently 
do  not  occur.  If  an  animal  has  a  memory  or  any  other  image, 
it  either  leads  directly  to  motor  expression  or  is  quickly  fol- 
lowed by  some  new  perceptual  experience.  A  dog  gives  evi- 
dence of  remembering  his  master  after  prolonged  absence, 
but  instead  of  this  memory  starting  a  train  of  reminiscences, 
it  leads  at  once  to  barking,  frisking  about,  and  vigorous  wag- 
ging of  the  tail.  Even  while  the  memory  image  lasts  it  may 
be  interrupted  by  a  word  or  a  gesture  from  his  master,  which 
starts  a  new  sensory  experience.  In  lower  animals  memory 
is  even  more  fragmentary. 

In  man  imagery,  and  more  especially  thought,  tends  to 
become  one  of  the  most  important  phases  of  mental  life.  A 
perception  arouses  a  thought,  this  thought  excites  another 
thought,  this  in  turn  a  third,  and  so  on.  A  long  series  of 
thoughts  may  arise  in  quick  succession,  each  independent  of 
external  stimulation  except  at  the  very  beginning.  Such  a 
train  of  thoughts  is  called  thinking. 

For  example,  you  hear  a  certain  humming  noise  and  think 
of  an  airplane.  This  suggests  the  thought  of  the  airplane 
post,  then  you  think  of  crossing  the  Atlantic,  then  of  a  great 
Atlantic  liner,  of  the  amount  of  coal  consumed  in  a  steamer, 
of  mining  coal,  of  a  miner  who  became  a  clergyman,  of  revival 
services,  of  gospel  hymns,  of  a  boy  choir,  of  the  Boy  Scouts, 
of  one  of  your  boyhood  games,  of  a  certain  school  teacher,  and 
so  on  through  a  long  series  of  thoughts. 

The  succession  of  mental  images  and  thoughts  is  com- 
monly called  association  of  ideas.  It  is  the  same  process  that 
we  examined  under  Recollection  (ch.  viii).  Recalling  a 
memory  is  merely  a  special  case  of  caljing  up  any  image  or 
thought;  in  fact,  when  the  memory  we  want  does  not  come 
immediately  we  usually  have  a  long  succession  of  other  ideas. 

The  principles  which  were  enumerated  as  *  laws  of  recol- 
lection *  are  fundamental  laws  of  the  association  of  ideas : 
(1)  Law  of  Similarity  and  Contiguity.    The  idea  aroused  by 


314  MENTAL  SUCCESSION  [ch.  xiv 

association  is  partly  similar  to  the  one  preceding  it,  and  the 
remainder  consists  of  experiences  that  were  formerly  experi- 
enced near  it  in  time  and  place.  (2)  Law  of  Frequency, 
Original  Vividness,  and  Recency.  As  between  different  pos- 
sible associations  with  a  given  idea,  that  one  is  most  likely  to 
follow  which  has  occurred  most  frequently,  or  which  was  orig- 
inally most  vivid,  or  which  has  occurred  most  recently. 

These  laws  of  association  are  not  arbitrary;  they  depend  on 
the  activity  of  the  nerve  impulses  in  the  brain.  In  passing 
from  center  to  center  the  current  always  follows  the  path  that 
offers  least  resistance.  The  resistance  is  diminished  by  the 
retention  of  the  effect  of  former  impulses  in  various  centers; 
similarity,  contiguity,  frequent  repetition,  original  strength 
of  impulse,  and  recency  of  excitation,  are  factors  which 
determine  the  relative  degree  of  resistance  of  several  possible 
pathways;  they  determine  which  way  thought  will  jump. 

In  addition  to  these  principal  factors  which  determine  the 
course  of  a  train  of  thought,  there  are  certain  secondary 
influences.  Our  general  bodily  condition  often  plays  an 
important  part  in  determining  the  direction  of  our  thinking. 
If  our  digestive  organs  are  working  well,  our  thoughts  are 
likely  to  dwell  on  pleasant  subjects  and  the  things  we  expect 
to  accomplish.  If  we  are  dyspeptic  we  are  prone  to  think  of 
difficulties  and  annoyances.  So,  with  the  same  thought  as  a 
starting-point,  we  may  proceed  along  two  entirely  different 
lines  of  thought  according  to  the  different  systemic  stimuli 
that  we  are  receiving.  The  reproductive  organs  affect  our 
thought  trains  in  the  same  way.  In  adolescence  thoughts 
tend  to  be  directed  at  times  rather  persistently  toward  sexual 
matters;  in  later  life  this  tendency  may  vanish  of  its  accord. 
The  influence  of  stimuli  from  the  respiratory  and  circulatory 
organs  on  thinking  is  less  marked  than  that  of  the  other 
internal  systems. 

Another  secondary  influence  on  the  direction  of  thought  is 
our  general  view  of  life  and  the  special  interests  that  appeal 


CH.  xiv]  STREAM  OF  THOUGHTS  315 

to  us.  The  trend  of  a  person's  life  determines  his  attitudes 
(eh.  xv),  and  his  attitudes  determine  very  largely  the  direc- 
tion of  his  thinking.  One  man's  thoughts  run  to  money, 
another's  to  athletics  and  sporting  subjects,  and  so  on.  We 
are  not  likely  to  notice  this  in  ourselves,  but  if  we  meet  one 
whose  interests  are  quite  different  from  our  own  we  are  often 
amazed  to  see  how  persistently  he  turns  the  conversation 
toward  his  own  special  interests  and  away  from  the  channel 
of  our  own  thoughts.  Fixed  ideas  are  an  exaggerated  and 
usually  pathological  form  of  this  tendency.  Certain  insane 
patients  persist  in  thinking  that  they  are  followed  by  ene- 
mies; their  thoughts  always  hark  back  to  this  fixed  delusion. 

All  these  secondary  influences  which  determine  the  direc- 
tion of  thought  may  be  summed  up  under  a  single  principle, 
the  Law  of  the  Personal  Equation:  As  between  different 
possible  associations  with  a  given  idea,  that  one  tends  to 
succeed  it  which  carries  most  interest  to  the  individual  or  is 
most  in  keeping  with  his  present  systemic  condition. 
V  Control  of  Thought.  —  Thoughts  are  not  the  direct  result 
of  external  stimuli.  The  first  thought  in  a  train  may  be  due 
to  something  we  see,  hear,  or  read,  but  those  that  follow 
depend  chiefly  on  processes  within  the  brain  itself.  To  this 
extent  thinking  is  '  free  ' ;  our  thoughts  are  not  driven  into  us 
by  external  forces,  like  our  perceptions.  We  ourselves  deter- 
mine their  course  in  accordance  with  the  principles  of  associa- 
tion. 

We  may  direct  our  thinking  along  certain  lines  by  taking 
a  definite  attitude  and  holding  a  given  problem  or  goal  before 
us.  You  wish  to  recall  a  certain  name,  and  this  desire  atti- 
tude may  direct  the  course  of  your  thinking  for  a  long  time. 
You  have  the  notion  of  a  half-complete  invention,  and  pro- 
ceed to  work  out  the  details  in  thought.  You  are  called  on  to 
solve  a  mathematical  problem  or  arrange  a  concert,  and  you 
think  over  various  possibilities  till  the  best  solution  or  pro- 
gram appears  in  thought.    In  all  such  cases  the  direction  and 


316  MENTAL  SUCCESSION  [ch.  xiv 

to  some  extent  the  material  of  your  thought  are  under  your 
own  control. 

Thinking  may  also  be  controlled  indirectly  by  motor  acts. 
You  tie  a  knot  in  your  handkerchief,  or  before  going  to  bed 
you  hide  a  stocking.  The  sight  of  the  knot  or  the  absence  of 
an  important  article  of  apparel  suggests  to  you  the  particular 
thought  that  induced  this  unusual  action.  The  association  is 
more  direct  when  you  place  in  your  hatband  a  letter  to  be 
mailed.  A  written  memorandum  —  '  draw  money,'  '  see 
Smith,'  '  return  umbrella  '  —  is  still  more  effective. 

Sometimes  a  thought  leaves  a  trace  in  the  nerve  structure 
which  arouses  another  thought  long  afterwards.  A  friend 
asks  you  to  dine  at  his  house  next  Wednesday.  The  thought 
makes  a  vivid  impression,  and  is  gone.  But  Wednesday 
afternoon  it  somehow  reappears  —  you  remember  the  en- 
gagement. (Not  always,  unfortunately!)  These  retention 
traces  seem  to  be  impressed  on  the  lower  centers  and  to  be  in 
some  way  connected  with  our  subconscious  life.  This  is 
indicated  by  some  of  the  phenomena  of  sleep  and  the  hyp- 
notic state.  You  determine  to  awake  to-morrow  morning  at 
6 :  30.  If  you  are  practiced  in  the  art,  you  actually  do  awake 
at  almost  exactly  that  hour.  The  controlling  medium  here  is 
subconscious. 

All  these  mental  and  behavior  operations  are  means  by 
which  an  individual  controls  his  own  thinking.  Thinking  is 
at  once  *  free '  and  '  determined.'  It  is  not  compelled  by 
outside  forces,  but  it  follows  definite  paths  determined  by 
the  make-up  of  our  nervous  system  and  by  the  attitudes 
built  up  through  our  entire  past  experience. 

A  train  of  thought  once  started  continues  indefinitely  till 
something  occurs  to  check  it.  An  intense  external  stimulus, 
producing  vivid  sensations  and  perceptions,  may  put  an  end 
to  your  thinking.  You  are  aroused  from  thought  by  hearing 
some  one  call  you,  or  by  some  striking  object  appearing  before 
your  eyes.    If  the  central  nerve  impulses  are  discharged  into  a 


CH.  xiy]  CONTROL  OF  THOUGHT  317 

motor  pathway,  and  you  start  to  act,  the  train  of  thought  is 
broken  off.  The  sudden  thought  that  it  is  time  to  attend  a 
class  sets  you  in  motion,  and  ends  your  reverie. 
^  Several  different  kinds  of  thought  trains  may  be  distin- 
guished: (1)  Casual  thinking,  which  is  subject  only  to  the 
general  laws  of  association.  This  is  the  ordinary  type,  which 
we  have  been  discussing.  (2)  Dreaming,  in  which  the  flow  of 
thought  is  modified  by  a  special  condition  of  the  brain  called 
sleep.  (3)  Hypnotic  thought  processes,  which  are  modified 
by  a  special  condition  of  the  nervous  system  called  hypnosis. 
(4)  Rational  thinking,  in  which  the  succession  is  determined 
by  a  special  mental  attitude  and  by  the  meaning  of  the 
thoughts. 

Dreams.  —  Sleep  is  a  special  condition  of  the  nervous  sys- 
tem. It  is  an  essential  part  of  the  repair  process  of  living 
creatures.  The  period  of  sleep  enables  the  organism  to  restore 
the  nervous  energy  used  up  by  the  activities  of  waking  life. 
In  man  the  period  covers  about  one-third  of  the  entire  day. 
As  a  physiological  condition,  sleep  is  just  as  normal  as  waking 
life,  but  the  mental  activities  that  occur  during  sleep,  called 
dreams,  present  many  unusual  features. 

The  distinctive  fact  in  dream  experiences  is  that  the  central 
neurons  are  almost  wholly  cut  off  from  their  sensory  and 
motor  connections.  The  synapses  which  join  the  sensory 
paths  with  the  brain  and  the  brain  with  the  motor  paths 
become  highly  resistant.  Only  intense  impulses  penetrate 
to  the  higher  centers,  or  impulses  which  play  a  prominent 
part  in  our  mental  life. 

During  sleep  we  are  not  ordinarily  affected  by  sounds, 
lights,  odors,  or  other  external  stimuli.  A  loud  sound  may 
penetrate  to  the  centers  and  arouse  us;  or  a  sound  which  pos- 
sesses unusual  personal  interest,  as  when  the  child's  fretting 
wakens  the  mother.  Organic  stimuli  are  often  very  effective; 
the  unpleasant  and  terrifying  dreams  known  as  nightmares 
are  attributable  to  indigestion.  Temperature  stimuli  suggest 


818  MENTAL  SUCCESSION  [ch.  xiv 

dreams  of  a  conflagration  or  of  walking  the  streets  unclad. 
Tactile  stimuli  are  rarely  effective.^ 

On  the  other  side  of  the  arc,  motor  discharge  is  checked, 
so  that  an  idea  which  in  waking  life  would  lead  to  speech, 
locomotion,  or  some  other  coordinated  activity  either  remains 
without  any  motor  expression,  or  at  most  produces  a  very 
slight  effect.  Occasionally  a  strong  motor  impulse  breaks 
down  the  resistance,  as  when  we  turn  over  in  bed  or  talk  in 
our  sleep.  Sleep-walking  occurs  when  specially  strong  motor 
impulses  find  effective  expression  without  wakening  the 
sleeper.  The  very  beginning  of  such  movements  serves  to 
waken  most  persons,  but  in  certain  individuals  and  under 
certain  conditions  somnambulism  proceeds  in  a  coordinated 
manner.  The  same  is  true  of  sleep-talking.  Where  the 
motor  impulse  does  not  produce  actual  movement,  slight 
twitching  movements  of  the  feet,  arms,  fingers,  and  throat 
often  occur.  These  incipient  movements  are  probably  more 
common  than  is  generally  supposed. 

There  is  usually  no  indication  to  an  outside  observer  that 
the  sleeper  is  dreaming,  and  the  sleeper  himself  may  recall 
nothing  on  waking.  This  is  not  conclusive  proof  that  the 
higher  brain  centers  are  inactive.  The  connection  between 
sleeping  thoughts  and  waking  thoughts  is  often  very  slender; 
we  sometimes  recall  a  dream  immediately  after  waking  only 
to  lose  all  recollection  of  it  soon  after.  When  any  one  tells  us 
that  he  never  dreams,  it  means  only  that  he  is  unable  to 
recall  dreams.  On  the  other  hand,  the  fact  that  many  dreams 
are  forgotten  does  not  justify  the  sweeping  conclusion  that 
the  sleeper  is  always  dreaming.  It  may  be  that  sometimes 
the  entire  cortex  is  inactive. 

Dream  life  differs  from  waking  life  principally  in  having 
a  much  narrower  field.  Because  the  cortical  centers  are 
largely  cut  off  from  sensory  impulses,  our  experiences  consist 

*  During  sleep  the  autonomic  processes  proceed  much  as  in  waking  life. 
The  breathing  is  more  regular  and  may  take  on  a  new  rhythm. 


CH.  xiv]  DREAMS  3W 

chiefly  of  imagery  and  thoughts.  This  seems  sufficient  to 
explain  the  fantastic  character  of  dreams  and  the  absurdities 
they  exhibit.  Dream  images  may  not  be  actually  more 
intense  than  the  imagery  of  waking  life;  but  since  there  are  no 
sensations  with  which  to  compare  them,  they  stand  out 
vividly  and  seem  to  be  actual  perceptions. 

The  strangeness  of  our  dream  experiences  is  due  to  this 
mistaking  of  our  thoughts  for  perceptions.  Any  one  of  your 
dream  pictures  might  readily  have  come  to  you  as  a  thought 
in  waking  life,  and  it  would  not  have  seemed  absurd.  For 
example,  it  is  entirely  natural  for  you  to  think  of  your  friends 
after  their  death.  But  you  do  not  see  your  dead  friends  in 
waking  life,  so  that  their  lifelike  appearance  in  dreams  is  often 
startling  —  after  you  awake.  At  the  time  it  seems  quite 
natural,  because  your  brain  centers  are  cut  off  from  one 
another,  so  that  you  do  not  associate  the  thought  of  the  man's 
being  dead  with  his  appearing  before  you. 

At  times  some  incongruity  may  be  noticed  during  the 
dream  itself,  and  may  puzzle  us.  I  was  once  surprised  in  a 
dream  to  see  a  friend  who  had  been  dead  for  some  years.  At 
once  I  recollected  that  the  report  of  his  death  was  a  mistake  — 
that  it  was  really  another  friend  who  died.^  This  supposed 
memory  recollection  was  merely  a  new  thought;  in  waking  life 
it  would  be  called  an  hypothesis.  We  would  suppose  the 
report  of  the  man's  death  was  a  mistake. 

The  incongruities  and  absurdities  in  the  succession  of  inci- 
dents in  dreams  are  to  be  explained  in  the  same  way.  A 
dream  is  really  a  train  of  thought  and  not  a  succession  of  per- 
ceptions.^  But  our  dreams  seem  at  the  time  to  be  real  per- 
ceptions.   After  we  awake  many  of  the  incidents  strike  us  as 

■  This  sometimes  happens  in  waking  life.  Some  time  ago  the  paper! 
falsely  reported  the  death  of  C.  R.  W.  Two  weeks  later  I  met  him.  Not 
having  heard  the  report  denied  I  was  far  more  astounded  than  in  the  dream 
incident. 

*  The  train  of  thought  described  on  page  313  might  easily  have  occurred  as 
a  dream;  and  we  would  have  considered  it  a  most  fantiistic  dream. 


320  MENTAL  SUCCESSION  [ch.  xiv 

absurd  because  real  beings  and  things  do  not  act  in  this 
fashion.  The  motion  pictures  have  succeeded  in  reproduc- 
ing in  visible  form  many  striking  effects  which  formerly  were 
obtained  only  in  dreams  and  vivid  imaginations.  A  study  of 
cinematograph  effects  will  help  us  to  appreciate  better  the 
construction  of  dreams. 

Since  dreams  are  thoughts,  and  not  voluntary  acts,  it  is  not 
surprising  that  honorable  persons  sometimes  dream  of  com- 
mitting dishonorable  actions,  such  as  lying,  stealing,  or  kill- 
ing. Every  one  thinks  of  these  acts,  though  in  waking  life  we 
usually  think  of  them  as  performed  by  some  one  else.  In 
dreams,  experiences  take  a  more  personal  form.  When  you 
dream  of  the  act  of  stabbing,  the  muscle-sense  memories  are 
more  vivid  than  in  waking  life,  and  the  brain  conditions  of 
volition  are  reproduced  without  the  motor  activity;  you  pic- 
ture yourself  as  performing  the  act.  One  need  not  be  alarmed 
at  such  dreams.  They  do  not  imply  any  hidden  flaw  in  a 
person's  character.     A  thought  is  by  no  means  always  a  unsh. 

Subconscious  life  plays  a  more  important  part  in  dreams 
than  in  waking  experiences.  Just  as  ideas  are  more  vivid 
through  the  absence  of  *  real '  perceptions,  so  subconscious 
experiences  are  apt  to  rise  to  the  surface  and  become  con- 
scious during  sleep,  because  there  are  fewer  intense  impulses 
in  the  brain  to  inhibit  them.  Our  general  attitudes  also 
influence  the  direction  of  our  dream  experiences  just  as  they 
direct  our  trains  of  thought  in  waking  life. 

To  sum  up,  dream  life  differs  from  waking  life  in  the  fol- 
lowing respects:  (1)  the  higher  brain  centers  are  cut  oS  from 
one  another  and  from  most  sensory  and  motor  paths;  (2) 
as  a  consequence,  our  experiences  are  fragmentary  and  inco- 
herent, and  thought  is  mistaken  for  real  perception;  (3)  our 
personal  control  is  diminished,  and  our  subconscious  tenden- 
cies are  more  prominent.  With  the  exception  of  these  differ- 
ences it  appears  that  dream  experiences  are  formed  in  the 
same  way  as  waking  thoughts,  and  that  dreams  (that  is, 


ca.  xiv]  DREAMS  S21 

trains  of  thought  in  sleep)  follow  the  same  laws  as  ordinary 
trains  of  thought  in  waking  life. 

Hypnosis.  —  Another  special  condition  of  the  nervous  sys- 
tem is  hypnosis.^  In  hypnosis  the  sensory  and  motor  paths 
are  not  cut  off  from  the  brain  as  in  sleep,  but  certain  pathways 
become  more  resistant,  while  others  are  unusually  open  to 
connection  with  the  centers. 

There  are  various  ways  in  which  a  person  may  be  hypno- 
tized: by  having  him  fix  his  gaze  on  a  bright  object,  or  talking 
to  him  in  a  droning  voice,  or  making  him  move  his  two  hands 
in  a  rhythmic,  circular  way.  He  will  then  gradually  pass 
into  the  hypnotic  state  and  lose  the  power  of  coordinating  his 
thoughts  and  controlling  his  actions. 

The  hypnotized  person  is  peculiarly  susceptible  to  sugges- 
tion. If  told  that  he  is  in  a  lake  he  immediately  begins  to 
make  swimming  movements.  If  the  hypnotizer  tells  him 
that  a  sheet  of  blank  paper  is  a  letter  from  a  friend  he  starts  to 
read  it.  His  actions  are  not  inhibited  as  in  sleep,  but  they 
are  controlled  by  the  mind  of  another  person.  Generally  the 
hypnotic  subject  is  governed  by  suggestions  from  the  one  who 
induced  the  hypnotic  state  and  he  pays  no  attention  to  any- 
one else.  The  process  of  hypnotizing  focuses  his  attention 
on  one  individual. 

In  normal  life  our  personality,  molded  by  past  experiences, 
inhibits  to  a  great  extent  the  effect  of  suggestion.  In  the 
hypnotic  state  these  inhibitions  are  lacking,  and  suggestions 
received  from  the  hypnotizer  are  all-powerful.  The  hyp^ 
notic  subject  does  what  he  is  told  to  do.  The  ordinary  sense 
of  fitness  is  lacking  and  he  will  unhesitatingly  perform  acts 
which  ordinarily  would  be  checked  by  the  feeling  of  absurdity 
or  fear  of  ridicule.  Suggestions  are  resisted  only  if  they  con- 
flict with  his  deepest  moral  sense. 

Hypnotic  suggestion  may  induce  anesthesia  of  one  or  more 

^  This  is  popularly  called  hypnotisir. .  Hypnotism  means  the  'theory  of 
hypnosis';  hypnosis  is  the  physiological  condition. 


322  MENTAL  SUCCESSION  [ch.  xiv 

of  the  senses.  The  subject  will  not  flinch  when  pricked  by  a 
needle  or  touched  with  a  hot  iron,  if  the  proper  command  is 
given.  At  other  times  the  hypnotic  suggestion  may  bring 
about  hyperesthesia;  the  subject  is  able  to  distinguish  one 
blank  sheet  from  another  when  told  that  they  are  photo- 
graphs of  different  people.  Hypnosis  is  a  condition  in  which 
the  thought-life  is  raised  to  the  focus;  perceptions  and  other 
experiences  are  subordinated  to  them.  The  stream  of  ex- 
periences in  hypnosis  follows  the  laws  of  thinking  rather 
than  the  laws  of  perception;  but  the  succession  of  thoughts  is 
constantly  guided  by  verbal  stimuli;  it  is  not  self-guiding,  as 
in  ordinary  thinking  and  in  dreaming. 

The  peculiar  behavior  of  a  hypnotized  subject  is  under- 
stood if  we  compare  him  with  a  dreamex'.  In  both  sleep  and 
hypnosis  our  thoughts  are  especially  vivid  and  are  mistaken 
for  perceptions.  In  sleep  the  flow  of  thoughts  is  ordinarily 
not  disturbed  by  outside  impressions  nor  accompanied  by 
motor  activity;  in  hypnosis  the  succession  of  thoughts  is 
determined  by  verbal  suggestions  from  another  person  and 
results  in  motor  activity  appropriate  to  the  thought,  but  not 
in  keeping  with  the  real  surroundings. 

Summing  up,  (1)  in  hypnosis  there  is  an  abnormal  condi- 
tion of  the  brain  centers;  (2)  the  hypnotic  subject  receives 
external  stimuli,  but  only  verbal  suggestions  have  conscious 
effect;  (3)  he  is  able  to  make  real  movements  instead  of  hav- 
ing merely  ideas  of  movement  and  speech  as  in  sleep;  (4) 
his  senses  may  be  sharpened  or  blunted  by  suggestions; 
(5)  his  actions  are  more  completely  controlled  by  suggestion, 
and  the  effects  of  this  suggestion  may  last  over  into  waking 
life.  For  practical  purposes  we  may  consider  hypnotic  expe- 
rience as  a  dream-like  mental  condition,  induced  and  con- 
trolled by  some  one  else,  instead  of  by  the  dreamer's  own 
mental  processes. 

Reasoning.  —  Rational  thinking,  or  reasoning,  is  another 
special  kind  of  thinking.    Dreams  gud  hypnosis  are  lower  and 


CH.  xivl  REASONING 

less  organized  than  casual  thinking,  while  reasoning  is  a 
higher,  more  adaptive  variety.  The  stream  of  rational 
thoughts  is  made  up  of  concepts  and  judgments;  the  succes- 
sion is  determined  by  their  meaning  instead  of  by  mere  simi- 
larity and  contiguity,  as  in  casual  thinking. 

In  our  waking  life  the  stimuli  from  the  external  world 
affect  us  in  haphazard  order,  so  that  the  succession  of  per- 
ceptions is  often  quite  unsystematic.  This  haphazard  con- 
nection of  unrelated  perceptions  tends  to  be  reproduced  in 
our  ordinary  trains  of  thought,  so  that  we  often  associate 
objects  or  events  which  are  not  actually  connected  in  nature. 
You  may  readily  think  of  gold  being  discovered  in  your  own 
back  yard,  and  go  on  to  picture  how  you  would  mine  it  and 
what  you  would  do  with  the  proceeds.  This  train  of  thought 
is  casual  thinking.  Very  different  were  the  thoughts  of 
Captain  Sutter  in  1848  when  gold  was  actually  found  at  his 
mill.  His  thinking  was  about  real  gold  and  the  real  conse- 
quences this  discovery  would  have  on  his  life. 

Reasoning  is  a  special  type  of  thinking  in  which  the  associa- 
tions correspond  to  processes  in  nature.  If  the  original  thought 
in  the  series  corresponds  to  real  things  or  events  or  facts, 
then  the  whole  train  will  represent  something  real.  If  we 
think  of  fourteen  dollars  added  to  a  pile  of  twenty-seven  dol- 
lars we  conclude  that  there  will  be  forty-one  dollars  in  the  pile. 
This  is  rational  thinking,  because  whenever  we  actually  carry 
it  out  the  result  tallies  with  our  thought.  Of  course  we  may 
not  have  the  fourteen  dollars  to  begin  with;  and  then  the 
result  does  not  happen  at  all.  But  the  thinking  is  rational 
just  the  same:  if  we  lack  the  dollars  we  can  try  it  with  pen- 
nies or  pebbles  or  eggs  or  pages  in  a  book  or  anything  else. 
The  conclusions  which  we  reach  through  reasoning  are  called 
inferences.  An  inference  is  a  new  thought,  based  on  associated 
meanings  or  values,  which  we  believe  will  tally  with  reality. 

How  has  man  gained  the  ability  to  reason  —  to  think 
rationally?    Reasoning  is  not  a  special  mental  power.     It  is 


324  MENTAL  SUCCESSION  [ch.  xiv 

an  outgrowth  of  ordinary  thinking,  due  to  two  circumstances: 
(1)  The  uniformity  of  nature.  We  learn  that  14+27  =  41 
because  we  always  obtain  that  result  —  with  dollars  and  eggs 
and  everything  else.  Nature  is  built  in  this  way.  Every- 
where and  in  every  phase  we  know  of,  the  workings  of  nature 
are  found  to  be  the  same.  (2)  The  complex  organization  of 
the  human  brain.  Our  language  centers  enable  us  to  devise 
arbitrary  words,  *'  fourteen,"  "  twenty-seven,"  etc.,  which 
are  symbols  instead  of  pictures.  By  means  of  these  symbols 
we  can  do  abstract  thinking  —  we  can  connect  fourteen  and 
twenty-seven  in  thought,  even  without  concrete  things  to 
work  with.  When  we  find  that  the  abstract  relation  actually 
holds  for  dollars  and  eggs  we  tend  to  apply  it  to  other  things; 
but  it  is  the  language  centers  that  enable  us  to  get  the  ab- 
stract ideas  in  the  first  place. 

There  are  many  other  varieties  of  reasoning  besides  arith- 
metic. Logic  is  one  of  them.  Man  has  discovered  that  if  A  is 
greater  than  B,  and  B  is  greater  than  C,  then  A  is  greater 
than  C.  If  John  is  older  than  Henry,  and  Henry  is  older 
than  William,  then  John  is  older  than  William.  These  and 
other  logical  relations  are  used  in  reasoning. 

Rational  thinking  is  applied  also  to  special  situations. 
When  you  think  of  Niagara  casually,  your  flow  of  thought 
may  follow  all  sorts  of  directions.  You  may  think  of  your 
chum's  trip  to  Niagara  and  BufiFalo;  that  you  would  like  to 
hunt  buffalo  in  the  plains;  that  a  carpenter's  plane  would 
smooth  a  man's  face  quicker  than  a  safety  razor;  and  this 
may  remind  you  of  meeting  a  fellow  named  Gillette.  None 
of  these  steps  of  thought  is  based  on  meaning;  they  depend 
merely  on  chance  similarity  of  sound  or  chance  contiguity. 
They  lead  you  nowhere.  But  if  you  think  of  actually  going 
to  Niagara,  your  train  of  thought  tends  to  become  rational: 
you  think  of  how  to  reach  the  place,  of  getting  a  time-table, 
drawing  money,  packing,  getting  to  the  station,  etc.  The 
initial  thought  in  this  case  is  not  the  word  Niagara,  but  the 


CH.  xiv]  REASONING  325 

concept  Niagara,  or  a  judgment  about  going  to  Niagara.  The 
science  of  logic  points  out  the  proper  use  of  reasoning.  A 
course  in  practical  logic  is  invaluable  in  training  us  to  reason 
correctly. 

Rational  thinking  sometimes  fails.  My  adding  machine 
gets  correct  results  in  summing  up  a  column  of  figures  oftener 
than  I  do.  People  have  been  known  to  miss  their  train  even 
when  the  trip  was  carefully  planned  out  beforehand.  These 
failures  are  due  to  a  variety  of  causes.  The  most  common 
cause  is  a  faulty  connection  in  the  brain.  The  rational  asso- 
ciation 4+7  =  11  becomes  very  strong  through  repeated  ex- 
perience, but  now  and  then  the  casual  association  4+7  =  12 
may  creep  in  when  we  add  up  a  column.  This  is  called  a 
fallacy.  Slips  in  reasoning  are  common  in  every  one's  life, 
but  a  careful  thinker  is  likely  to  discover  the  error  by  noting 
some  inconsistency  in  the  results. 

Sometimes  the  failure  is  due  to  our  expecting  too  great 
uniformity  in  nature.  Encke's  comet  did  not  return  quite 
as  soon  as  the  calculations  predicted:  something  not  foreseen 
by  astronomers  delayed  it  on  the  way.  Your  trip  to  the 
Falls  may  be  frustrated  by  a  new  time-table  or  a  railroad  ac- 
cident. In  such  cases  there  is  no  fallacy  in  your  inference; 
there  is  merely  ignorance  of  some  important  factor  in  the 
situation. 

A  superstition  is  imagining  some  relation  in  nature  which 
does  not  really  exist.  The  ancients  reasoned  that  a  certain 
plant  must  be  a  remedy  for  heart  trouble,  because  its  leaves 
are  heart-shaped.  If  you  pronounce  some  mystical  word,  the 
winds  or  the  mountains  will  obey  your  commands,  because 
human  beings  obey  you  when  you  speak  with  authority. 
Thirteen  at  the  table  must  mean  death  to  one  of  the  com- 
pany, because  there  were  thirteen  at  the  Last  Supper,  Once 
these  fanciful  connections  are  formed  in  our  minds  they  are 
hard  to  eradicate,  —  especially  if  testing  their  falsity  might 
mean  death  to  the  experimenter.     Yet  the  only  way  to  dis- 


826  MENTAL  SUCCESSION  [ch.  xiv 

tinguish  between  a  correct  inference  and  a  superstition  is  for 
some  one  to  try  it  out  and  see  what  happens. 

There  is  another,  more  insidious  misuse  of  reasoning. 
Often  we  arrive  at  a  decision  by  some  train  of  casual  thinking 
and  then  try  to  make  our  decision  look  rational  by  construct- 
ing a  plausible  explanation.  You  advocate  opening  a  new 
street,  or  laying  a  sidewalk,  or  putting  in  more  lights,  on  the 
ground  of  great  public  need;  but  you  originally  thought  of 
the  improvement  only  as  a  benefit  to  yourself  personally. 
You  are  perfectly  sure  it  is  the  scenery  that  decides  you  to 
take  that  stroll  —  not  the  girl  you  are  likely  to  meet  on  the 
way.  The  salesman  knows  a  hundred  reasons  why  his  goods 
are  better  than  any  others;  and  he  honestly  believes  them. 
This  mental  process  of  constructing  artificial  reasons  is  called 
jrarfignflitaaiiftZL    If  you  analyze  your  real  motives  you  will  be 


surprised  to  find  how  frequently  the  rationalizing  process 
occurs,  and  how  strong  is  the  temptation  to  use  it.  The 
teacher  of  practical  ethics  might  well  begin  his  instruction 
with  the  injunction:  "  Be  honest  with  yourself." 

Reasoning  is  the  most  important  step  in  the  growth  of 
adaptive  behavior.  It  enables  us  to  anticipate  events  and 
prepare  for  them  beforehand.  Rational  thinking  is  most 
effective  when  it  is  supplemented  by  casual  thinking.  We 
picture  imaginary  situations  and  consider  how  we  would  act 
or  how  nature  would  act.  When  we  work  with  scientific 
:  hypotheses  we  combine  the  two  types  of  thinking. 

The  General  Stream  of  Experiences.  —  Our  conscious  Ufe 

( is  a  vast  stream  comprising  experiences  of  many  sorts.    With 

)  the  exception  of  perceptions  and  thoughts  we  rarely  have  a 

long  uninterrupted  succession  of  any  one  kind  of  experience. 

A  feeling  usually  brings  about  action,  which  transforms  the 

.    feeling  into  an  emotion.     An  emotion  is  apt  to  exhaust  itself 

<    quickly  and  pass  over  into  thought  or  volition  or  speech. 

Volition  results  in  movements  which  usually  change  our  situ- 

^  ation  and  bring  about  new  perceptions.    In  the  general  vista 


CH.  xivl        STREAM  OF  EXPERIENCES  327 

of  experience  there  may  be  long  unbroken  stretches  of  per- 
ceptions and  long  unbroken  stretches  of  thought;  between 
these,  small  patches  of  other  experiences  are  intersp)ersed. 

In  almost  every  human  being,  whether  civilized  or  savage, 
perceptions  are  most  frequent  and  form  the  core  of  mental 
life.  Among  educated  adults  of  civilized  communities 
thought  and  imagery  occupy  a  good  second  place,  while 
among  primitive  peoples  the  emotional  life  is  more  impor- 
tant than  thought  and  imagery.  Motor  experiences  —  voli- 
tion and  language  —  generally  rank  ahead  of  the  emotions 
among  civilized  races. 

Our  mental  life  at  any  instant  may  include  more  than  one 
experience:  a  perception,  a  thought,  and  a  volition  may  all  be 
present  together,  one  of  them  being  vivid,  the  rest  marginal 
or  subconscious.  Their  relations  change;  the  perception 
may  fade  into  the  background,  and  the  thought  which  was 
indistinct  may  advance  to  the  foreground.  When  you  are 
out  walking  with  a  friend  your  attention  oscillates  between 
the  perception  of  things  about  you  and  the  thoughts  and 
utterances  of  your  conversation.  In  reality  both  percep- 
tion and  thought  are  present  all  the  time;  the  change  is  in 
the  focus  of  attention  —  in  the  relative  vividness  of  the  two. 

What  kind  of  experience  will  occupy  the  focus  of  attention 
at  any  given  moment  is  determined  by  the  relative  strength  of 
the  various  nerve  impulses  occurring  in  the  brain  at  that 
moment.  This  depends  partly  on  the  intensity  of  stimula- 
tion. A  loud  noise,  a  flash  of  light,  a  sharp  blow,  or  a  muscu- 
lar strain  may  force  a  perception  upon  us  and  crowd  all  other 
experiences  out  of  the  focus.  But  unless  the  new  stimulus  is 
very  intense  it  finds  a  rival  in  the  nerve  impulses  that  are 
already  active  in  the  brain.  The  new  sensory  nerve  impulse 
may  be  wholly  or  partly  inhibited  by  the  existing  central 
impulses,  or  it  may  combine  with  them.  The  direction  of  our 
interest  and  attention  is  important  in  determining  what  the 
effect  will  be.    If  you  are  interested  in  following  a  trail  in  the 


828  MENTAL  SUCCESSION  [ch.  xiv 

woods,  the  most  trivial  signs  will  strike  your  attention  — 
a  blazed  tree,  a  broken  twig,  or  a  footprint;  for  the  time  being, 
the  perceptive  life  dominates.  A  geometrician  like  Archi- 
medes, on  the  other  hand,  may  be  so  absorbed  in  reasoning 
out  a  problem  that  no  external  stimulus  will  move  him. 
An  emotional  man  flies  into  a  violent  rage  or  into  wild  exul- 
tation over  some  event  that  arouses  merely  perception  or 
thought  in  another. 

In  short,  the  succession  of  our  experiences  in  the  general 
stream  of  mental  life  depends  both  on  stimulation  and  on  the 
make-up,  training,  and  present  condition  of  our  nervous  sys- 
tem. It  follows  in  part  the  laws  of  the  stream  of  perceptions, 
and  in  part  the  laws  of  the  stream  of  thought.  Our  present, 
persistent  personality,  which  has  been  built  up  out  of  all  our 
past  experiences,  is  an  all-important  factor  in  determining 
the  course  of  the  stream. 

The  Stream  of  Actions.  —  Mental  life  includes  not  merely 
our  experiences  but  our  actions.  These  also  form  a  series. 
Every  act  involving  muscular  contraction  stimulates  the 
muscle  sense  and  may  lead  to  another  act  or  to  a  continuation 
of  the  same  activity.  We  are  seldom  entirely  quiescent. 
When  we  are  not  actually  contracting  some  muscles,  we  are 
usually  maintaining  their  tension.  Try  at  the  present  mo- 
ment to  relax  your  facial  muscles,  or  your  legs,  or  your  arms 
completely.  You  will  find  that  there  is  some  muscular  ten- 
sion in  these  members,  though  you  may  have  supposed  they 
were  quite  relaxed. 

Even  simple  acts,  like  catching  a  ball,  involve  a  series  of 
coordinated  movements  lasting  an  appreciable  time.  And 
when  the  act  is  completed  it  generally  brings  about  a  new 
situation  which  demands  another  response.  When  the 
fielder  has  caught  the  ball,  he  has  to  throw  it;  or  if  his  play 
ends  the  innings  he  is  no  longer  wanted  in  the  field  and  is 
expected  to  run  in.  When  the  game  is  over  he  has  to  dress, 
go  home  and  prepare  for  dinner,  or  study,  or  see  a  friend. 


CH.  xiv]  STREAM  OF  ACTIONS  329 

Rarely,  except  during  sleep,  is  the  response  life  resting. 
Waking  life  is  a  flow  of  actions  —  a  continuous  succession  of 
responses,  one  after  the  other,  each  determined  by  our  suc- 
cessive experiences. 

Summary.  —  The  experiences  and  responses  which  have 
been  examined  in  the  foregoing  chapters  are  not  detached 
events.  They  form  a  continuous  stream  or  succession. 
The  flow  of  experiences  depends  partly  on  what  effects  us 
from  outside,  and  partly  on  our  inherited  and  acquired  men- 
tal conditions.  In  the  case  of  perceptions,  the  external 
stimuli  are  largely  responsible  for  the  course  of  experience; 
in  thought,  the  succession  is  determined  by  the  mental  prin- 
ciples of  association. 

Besides  the  ordinary  or  casual  trains  of  thought,  thinking 
has  two  somewhat  abnormal  varieties  called  dreaming  and 
hypnotic  experiences,  which  occur  in  sleep  and  hypnosis, 
respectively. 

A  higher  form  of  thinking  occurs  when  the  association  is 
based  on  the  meanings  and  values  of  our  thoughts.  This  is 
called  reasoning.  The  materials  used  in  reasoning  are  con- 
cepts and  judgments;  the  inferences  which  we  draw  from 
them  tend  to  correspond  to  real  events  or  general  truths  of 
nature. 

Our  receptive  life  is  a  succession  of  perceptions,  thoughts, 
reasoning,  dreams,  emotions,  volitions,  and  other  experiences, 
which  come  and  go,  wax  and  wane,  continually.  Our  active 
life  is  a  succession  of  responses. 

Practical  Exercises: 

69.  Test  a  person's  association  time  with  a  stop-watch.  Choose  some 
noun  or  verb  and  say  it  distinctly,  at  the  same  time  starting  the  watch. 
Instruct  the  subject  to  call  out  the  first  word  which  he  associates  with 
your  stimulus  word,  then  the  first  word  associated  with  this  second 
word,  and  so  on  till  he  has  made  (and  uttered)  10  associations.  Stop 
the  watch  and  note  the  time.  Repeat  several  times  and  find  his  av- 
erage association  time  for  a  single  association. 

70.  Sit  with  pencil  and  paper  and  note  the  first  word  you  see  in  a  book 
opened  at  random.    Write  down  the  first  idea  which  it  suggests,  then 


830  MENTAL  SUCCESSION  [ch.  xiv 

the  first  idea  suggested  by  this  latter,  and  so  on  for  a  series  of  15  or  20 
successive  associations.  Examine  each  association  and  determine 
which  of  the  laws  of  association  are  responsible  for  its  formation. 

71.  Chain  reaction.  Let  a  group  of  persons,  including  the  experimenter, 
join  hands  in  a  circle.  The  experimenter  holds  a  stop-watch.  With- 
out warning  he  presses  the  next  person's  hand,  starting  the  stopHwatch 
with  the  same  movement.  The  instant  the  second  person  feels  the 
pressure  he  presses  the  hand  of  the  third;  and  so  on,  around  the 
circle.  When  the  last  person  presses  the  experimenter's  hand,  the 
experimenter  stops  the  watch.  The  average  reaction  is  found  by 
dividing  the  total  time  by  the  number  of  persons  in  the  circle,  since 
each  has  reacted  once. 

72.  Analyze  the  succession  of  experiences  in  one  of  your  dreams.  Report 
what  laws  of  association  operate;  explain  if  possible  the  incongruities. 

73.  Attend  carefully  to  a  conversation  between  two  persons.  Note  which 
associations  are  'rational'  and  which  are  'casual.' 

74.  Examine  the  succession  of  your  experiences  during  the  past  10  minutes 
and  study  the  relation  between  perceptions  and  thoughts  in  the  series. 

References: 

On  association  and  reaction  time:  H.  C.  Warren,  History  of  the  Association 
Psychology,  ch.  8  ;  C.  G.  Jung,  Studies  in  Word-Association  (trans.). 

On  dreams:  M.  de  Manacelne,  Sleep  (trans.);  S.  Freud,  Interpretation  of 
Dreams  (trans.). 

On  hypnosis  and  suggestion:  A.  Moll,  Hypnotism  (trans.). 

On  reasoning:  W.  James,  Principles  of  Psychology,  ch.  22;  W.  B.  Pills- 
bury,  Psychology  of  Reasoning. 


K 


CHAPTER  XV 
HUMAN  CHARACTER 


Permanent  Mental  Conditions.  — Experiences  leave  traces 
in  the  structure  of  the  nervous  system.  These  retention 
traces  are  revived  in  the  form  of  memories  or  imaginations, 
and  they  tinge  our  perceptions  with  a  *  sense  of  familiarity.' 

Besides  this,  retention  has  another  and  far  more  important 
eflFect  on  mental  life.  When  the  same  sort  of  experience  is 
repeated  over  and  over  again,  the  trace  may  deepen  into  a 
more  or  less  permanent  set  of  the  nerve  substance.  These 
enduring  traces  affect  our  way  of  receiving  stimuli,  and  lead 
to  stereotyped  behavior.  The  pathfinder  watches  for  signs 
of  the  trail  in  the  forest;  the  experienced  football  player  finds 
the  gaps  in  the  opposing  line;  the  pessimist  always  sees  the 
dark  side  of  things.  Each  one,  by  rep>etition  of  the  same  sort  \ 
of  experience,  has  acquired  a  mental  attitude  toward  certain 
features  of  the  environment.  As  time  goes  on,  these  atti- 
tudes tend  to  become  more  stereotyped  and  to  cover  a  wider 
territory.  Each  trade  has  its  own  vocabulary  and  code. 
One  can  often  guess  rather  accurately  a  man's  occupation  by 
the  sort  of  words  and  phrases  he  applies  to  ordinary  situa- 
tions. The  sailor  tells  you  about  the  house  on  the  starboard 
side  of  the  road;  the  chauffeur,  acting  as  butler,  parks  the 
dishes  on  the  serving  table. 

A  great  quantity  of  attitudes  are  built  up  out  of  material 
furnished  by  the  external  senses.  These  fixed  ways  of  per- 
ceiving and  thinking  are  called  cognitive  attitudes.  The  sum- 
total  of  our  cognitive  attitudes  make  up  our  intellectual  char- 
acter, or  intellect.  In  the  same  way  all  the  attitudes  based  on 
a  person's  systemic  life  combine  to  form  his  affective  char- 
acter, or  temperament;  his  motor  attitudes,  taken  together. 


832  HUMAN  CHARACTER  [ch.  xv 

make  up  his  motor  character  or  skill;  a  man's  social  attitudes 
determine  his  moral  character  or  morality.  Character  is  a  more 
permanent  and  fundamental  condition  than  the  attitude. 
It  is  made  up  of  a  vast  number  of  attitudes. 

The  several  phases  of  an  individual's  character  are  not 
independent.  They  interact  upon  one  another.  Your 
temperament  may  be  modified  by  your  moral  character,  or 
by  your  intellect.  Your  mental  nature  is  the  sum-total  of 
all  the  permanent  mental  conditions  that  have  developed 
within  you  up  to  the  present.  This  all-embracing  result  of 
mental  organization  is  called  personality.  Personality  in- 
cludes our  innate  tendencies,  our  attitudes,  and  our  char- 
acter. 

Attitudes,  character,  and  personality  are  not  particular 
experiences,  but  permanent  mental  conditions  which  underlie 
experiences.  Attitudes  change  very  gradually.  They  are 
molded  slowly;  once  formed  they  alter  only  as  the  trend  of 
experience  takes  another  direction.  The  city-bred  man  takes 
a  citified  attitude  toward  the  world;  it  is  only  after  long 
experience  with  country  life  that  he  can  change  this  attitude 
and  see  the  world  with  the  countryman's  eye.  The  country- 
man is  bewildered  and  helpless  on  his  first  visit  to  the  city. 

Character  alters  far  more  slowly  than  attitudes.  Person- 
ality undergoes  a  still  more  gradual  development  and  trans- 
formation. The  growth  of  a  man's  personality  covers  the 
entire  period  of  his  lifetime. 

Attitude 

Nature  and  Classes  of  Attitudes.  —  A  mental  attitude  is 
a  permanent  set  of  our  mental  and  nervous  system  which 
modifies  the  effect  of  stimuli  and  determines  how  we  shall 
respond.  Your  chum  lands  a  fine  job.  How  do  you  take  the 
news?  Are  you  *  tickled  to  death,'  or  do  you  envy  him  the 
good  luck  which  has  not  come  to  you?  The  news  is  the  same 
in  either  case;  your  attitude  and  your  behavior  are  different. 


CH.  xv]  CLASSES  OF  ATTITUDES  333 

Because  attitudes  are  not  particular  experiences  we  cannot 
examine  them  like  perceptions  and  emotions.  They  may  be 
studied  through  the  motor  expressions  which  they  bring 
about.  An  alert  attitude,  a  sullen  attitude,  a  credulous  atti- 
tude, almost  inevitably  lead  to  different  kinds  of  behavior. 
The  popular  meaning  of  the  word  attitude  emphasizes  this. 
It  means  a  *  motor  posture.'  In  psychology  attitude  means 
this  and  more;  it  includes  the  mental  condition  which  governs 
the  motor  posture. 

Every  attitude  is  the  product  of  repeated  experiences.  If 
you  live  in  a  certain  environment  you  are  likely  to  develop 
certain  attitudes  which  belong  to  that  environment.  The 
street  urchin  acquires  a  whole  raft  of  attitudes  from  his  sur- 
roundings which  the  farmer's  lad  could  never  develop.  City 
life  develops  alertness;  country  life  promotes  observation 
of  nature.  Our  attitudes  are  sieves  through  which  certain 
experiences  are  strained  out  and  others  are  concentrated. 
Attitudes  begin  to  develop  early  in  life.  Fear  of  the  dark 
or  of  thunder  can  usually  be  traced  to  some  experience  in 
childhood.  It  may  take  years  to  eradicate  certain  impres- 
sions made  by  the  tales  of  an  ignorant  nurse.  You  were  told 
of  the  man  who  was  tossed  so  high  that  he  stayed  up  in  the 
air,  floating  about  forever;  the  notion  sticks  by  you  long  after 
you  are  familiar  with  the  principle  of  gravitation. 

Attitudes  are  classed  according  to  the  sort  of  experience 
that  develops  them.  The  attitude  which  grows  up  in  connec- 
tion with  perceptions  and  ideas  is  called  interest.  Our  feeling 
experiences  develop  a  type  of  attitude  called  desire,  and  our 
simple  motor  experiences  develop  the  attitude  of  attention.^ 
These  three  primary  attitudes  dominate  our  mental  life  and 
exert  a  powerful  influence  on  every  particular  experience  of 
the  corresponding  type. 

^  Notice  the  two  different  uses  of  the  word  aUention;  (1)  it  denotes  the 
mental  process  of  focusing  an  impression  and  making  it  more  vivid  (ch.  vi) ; 
(2)  it  also  means  the  motor  type  of  attitude. 

f 


334  ATTITUDE  [ch.  xv 

In  popular  language  we  say  that  feelings  cause  desire,  that 
the  things  which  we  perceive  arouse  interest.  The  truth  is 
that  the  desire  attitude  and  the  interest  attitude  are  the 
product  of  a  life-time;  they  are  our  way  of  receiving  incoming 
stimuli.  Interest  is  not  something  in  the  mind  which  is 
aroused  by  what  we  see;  it  is  a  mental  bias  or  set  which  causes 
certain  perceptions  or  ideas  to  be  especially  vivid  and  per- 
sistent. Attention  is  not  really  something  that  we  turn 
toward  an  experience,  but  it  is  a  mental  tendency  to  adjust 
our  muscles  this  way  or  that  according  to  the  situation. 

The  attitudes  that  grow  out  of  emotion,  thought,  and  other 
secondary  experiences  develop  differently  from  interest, 
desire,  and  attention.  Instead  of  becoming  uniform  they 
take  on  many  different  forms.  The  emotional  attitudes  are 
especially  rich  in  their  shading.  It  is  not  difficult  to  dis- 
tinguish between  a  friendly,  an  affable,  a  gracious,  and  a 
devoted  attitude;  if  you  train  yourself  to  study  human  nature 
you  will  be  able  to  distinguish  between  the  domineering, 
pompous,  arrogant,  overbearing,  lordly,  condescending,  and 
superior  attitudes  which  men  in  authority  almost  inevitably 
assume.  Language  attitudes  are  few  in  number  and  are  not 
especially  significant.  Attitudes  of  thought  and  moral  atti- 
tudes are  more  numerous.  All  these  secondary  attitudes  give 
diversity  to  human  character.     [Table  XIV.] 

i  Table  XIV. —  Human  Attitudes 

Attitude  Mental  Basis 

Primary: 

Interest  Perception,  Ideation 

Desire  Peeling 

Attention  Conation 
Secondary: 

Dispositions  Emotion,  Sentiment 

Appreciation  Thought 

Conscience  Social  situation 

Proclivities  Volition 

Language  attitudes  Language 

Ideal  attitudes  Ideab 


CH.  xv]     INTEREST,  DESIRE,  ATTENTION  535 

Interest,  Desire,  and  Attention.  —  The  three  primary  at- 
titudes —  interest,  desire,  and  attention  —  generally  work 
together;  their  influence  is  observed  in  almost  every  experi- 
ence. Suppose  you  are  watching  a  baseball  game.  The 
chances  are  that  you  are  there  on  account  of  your  interest  in 
the  game.  As  you  watch  the  significant  plays  you  look  at  the 
actions  of  the  players  with  interest  —  with  a  very  different 
attitude  from  your  cursory  perception  of  the  foul-line  or  the 
glove  accidentally  dropped  on  the  turf.  If  you  are  interested 
in  one  of  the  teams,  you  have  a  desire  that  this  team  shall  win. 
At  critical  points  in  the  game  this  desire  becomes  strong  and 
causes  violent  heart-beating,  deep  breathing,  and  perhaps  a 
feeling  of  *  goneness  '  in  the  pit  of  your  stomach.  You  attend 
to  each  play  through  slight  motor  reactions.  You  knit  your 
brows,  clench  your  fists,  fix  your  eyes;  aU  these  are  attention 
attitudes. 

These  three  attitudes  are  so  closely  connected  together  that 
it  is  not  easy  to  distinguish  them.  In  popular  language  they 
are  often  confused.  We  speak  of  attention  when  we  really 
mean  interest.  This  confusion  may  be  avoided  if  we  practice 
careful  observation  of  our  own  experiences.  Attention  is  our 
motor  attitude,  interest  is  our  attitude  toward  the  perception 
or  idea,  making  it  more  vivid  and  prominent. 

Attention  shows  itself  in  muscular  adjustment  or  tension, 
which  enables  us  to  receive  impressions  better.  When  you 
follow  a  moving  object  with  the  eye,  the  eye  movement  is 
the  expression  of  your  attention  attitude.  It  is  not  the 
significant  response  to  the  stimulus,  but  it  helps  you  to  per- 
ceive the  object  better,  and  in  this  way  you  are  able  to 
respond  more  suitably  when  the  time  comes.  Your  interest 
in  the  moving  object  is  the  attitude  that  makes  this  object 
*  stand  out  prominent  in  consciousness.'  Moving  objects, 
flashing  signs,  loud  noises,  and  other  intense  stimuli  are  likely 
to  arouse  attention,  even  though  they  lie  outside  our  usual 
line  of  interest.     This  is  called  involuntary  attention  and  it 


336  ATTITUDE  [ch.  xv 

usually  carries  with  it  involuntary  interest.  A  prosy  speaker 
pounds  on  the  desk  and  makes  his  hearers  sit  up  and  take 
notice;  so  far  as  his  subject-matter  goes  they  would  prefer  to 
relax  and  enjoy  a  nap. 

In  general,  a  person's  interest  follows  certain  definite  lines; 
it  brings  out  the  things  he  is  most  accustomed  to  observe  and 
the  ideas  he  is  most  accustomed  to  think.  In  reading  the 
morning  paper  one  man  spends  most  time  on  the  stock  quo- 
tations, another  on  the  sporting  page,  a  third  man  on  mur- 
ders and  accidents,  a  fourth  on  the  foreign  news  and  editorials. 
The  line  of  your  general  interest  makes  some  particular  part 
of  the  paper  loom  large  in  your  mind  and  fixes  your  attention. 

Desire  differs  from  interest  and  attention  in  having  two 
opposite  forms,  corresponding  to  the  two  feelings  of  appetite 
and  aversion.  Our  attitude  toward  pleasant  experiences  is 
called  satisfaction.  If  we  are  experiencing  something  un- 
pleasant and  imagine  some  pleasant  alternative,  our  attitude 
is  dissatisfaction  and  something  more:  it  carries  with  it  a 
picture  of  removing  the  unpleasantness  or  transforming  it 
into  pleasantness.     This  attitude  is  called  want,  or  need. 

Satisfaction  is  less  distinctive  than  want.  In  satisfactory 
situations  the  pleasantness  of  the  experience  itself  dominates, 
and  the  attitude  usually  plays  an  unimportant  part.  But  in 
unpleasant  situations  the  attitude  of  '  want '  tends  to  share 
the  focus  with  the  feeling  of  unpleasantness. 

In  discussing  memory  we  found  that  definite  systemic 
memories  and  systemic  ideas  rarely  occur.  Instead  of 
remembering  this  feeling  or  that,  we  generally  have  a  want, 
which  is  an  attitude  due  to  many  past  feelings.  You  want  a 
motor  car  because  of  imagined  pleasure.  You  want  break- 
fast not  merely  on  account  of  present  hunger,  but  because 
you  recall  the  satisfaction  of  eating  breakfast  on  other  occa- 
sions. The  desire  for  honors,  wealth,  praise,  success,  rests  on 
similar  grounds.  Want  leads  to  motor  activity  which  tends 
to  remove  the  unpleasantness  or  to  bring  about  the  desired 


CH.  xv]     INTEREST,  DESIRE,  ATTENTION  337 

pleasantness.  Our  actions  do  not  always  succeed  in  accom- 
plishing this.  But  it  is  characteristic  of  the  want  attitude 
that  it  spurs  us  to  action.  As  our  mental  adjustment  be- 
comes perfected,  we  become  better  able  to  do  the  right  thing, 
which  in  this  case  is  to  fulfill  the  desire.  When  this  is  accom- 
plished the  want  gives  way  to  satisfaction. 

Interest,  desire,  and  attention  enable  us  to  guide  and  con- 
trol the  course  of  our  experiences  and  actions.  In  this 
respect  they  belong  among  the  motives  of  human  life. 

Emotional  Attitudes.  —  No  phase  of  human  life  is  more 
worthy  of  study  than  our  emotional  attitudes,  or  dispositions. 
To  one  who  has  learned  to  interpret  them,  they  furnish  one 
of  the  very  best  indications  of  a  man's  personality.  In  civi- 
lized society,  emotional  expression  is  usually  repressed;  only 
critical  situations  call  forth  unbridled  displays  of  emotion. 
But  the  emotional  attitude  is  rarely  washed  out  completely. 
The  emotion  of  joy  simmers  down  into  a  cheerful  disposition; 
repressed  emotions  of  anger  lead  to  a  hostile  disposition.  In 
talking  with  a  person  you  can  usually  tell  whether  he  is 
annoyed  or  pleased,  whether  he  is  well-disposed  toward  you 
or  defers  to  you  or  considers  himself  a  bit  above  you,  by 
something  in  his  manner  or  tone,  if  not  by  his  words  and 
actions.  You  know  at  once  if  a  stranger  is  distrustful  or 
ready  to  accept  you.  You  can  often  tell  that  a  certain  man 
is  worried  or  overburdened  before  he  says  a  word. 

Our  most  casual  acts  and  words  may  be  thoroughly  satu- 
rated with  concentrated  emotion.  "  They  left  me  out." 
"  In  my  humble  opinion  — ."  "  Won't  you  listen  to  me?" 
Who  cannot  guess  the  emotional  background  of  these  phrases ! 
The  jx)ker  player  trains  himself  to  suppress  or  disguise  even 
the  simplest  manifestations  of  feeling,  and  the  business  man 
endeavors  to  obliterate  them  with  more  or  less  success. 
Often  it  becomes  a  contest  between  concealment  and  detec- 
tion —  not  unlike  the  struggle  for  supremacy  between  defen- 
sive armor  and  penetrative  shells.     If  you  cannot  get  rid  of 


338  ATTITUDE  [ch.  xv 

your  own  emotional  display,  you  can  at  least  leam  to  detect 
the  slight  twitchings  of  certain  muscles  and  inflections  of  the 
voice  in  other  persons,  which  will  reveal  to  you  their  emo- 
tional dispositions. 

Popular  psychology  distinguishes  between  a  disposition, 
which  is  a  more  or  less  permanent  attitude,  and  a  mood,  which 
is  liable  to  frequent  fluctuation.  The  distinction  seems  valid, 
but  it  is  of  social  rather  than  psychological  importance. 
Our  emotional  attitudes  become  established  by  slow  degrees, 
and  the  border  line  between  a  passing  mood  and  a  permanent 
disposition  is  indefinite. 

Sentimental  attitudes  are  closely  related  to  emotional  atti- 
tudes; this  probably  accounts  for  the  popular  confusion 
between  emotions  and  sentiments.  Doubt  gives  rise  to  a 
perplexed  attitude;  strong  beUef  mingled  with  strong  dis- 
belief produces  a  biased  or  prejudiced  disposition.  Certain 
dispositions  are  derived  directly  from  instinctive  tendencies, 
with  no  emotional  tinge  whatever;  as  for  instance  the  miserly 
and  orderly  dispositions. 

Nearly  every  class  of  emotion  develops  a  corresponding 
attitude  or  disposition.^  In  Table  XV  only  the  most  notice- 
able dispositions  are  given;  it  would  be  hopeless  to  include 
the  numerous  finer  shades.  The  great  wealth  of  emotional 
attitudes  is  in  striking  contrast  with  the  one  single  form  of 
the  interest  attitude. 

Even  oiu-  judgments  of  fact  are  usually  tinged  with  emo- 
tional bias.  Read  any  accoimt  of  the  American  Civil  War 
written  in  the  'CO's  or  70's  —  or  even  the  '80's.  Notice  the 
adjectives  appUed  to  Lee  and  Davis  by  Northern  historians, 
or  to  Lincoln,  Grant,  and  Sherman  if  the  writer  is  a  South- 
erner. It  fairly  startles  us  to  find  our  own  countrymen  mani- 
festing these  emotional  attitudes  in  writing  plain  history. 
The  school  histories  of  an  earlier  generation  took  a  similar 
epaotional  attitude  toward  the  '  Tories  '  and  '  red-coats  ' 
1  Compare  Table  XV  with  Table  VIII  (p.  215). 


CH.  XV] 


EMOTIONAL  DISPOSITIONS 


339 


Table  XV. —  Human  Dispositions 


1.  Expressive 

2.  Reproductive 

Attitude 

Emotion 

Attitude 

Emotion 

Cheerful 

Joy 

Affectionate 

Love 

Despondent 

Grief 

Lascivious 

Lust 

Dazed 

Shock 

Jealous 

Jealousy 

Frivolous 

Mirth 

Motherly 

Tenderness 

Zealous 

Ecstasy 

Erratic 

Restiveness 

Romantic 

Exuberance 

Devout 

Wonder 

8.  Defensive 

4.  Aggressive 

Attitude 

Emotion 

Attitude 

Emotion 

Cowardly 

Fear 

Hostile 

Anger 

Courageous 

" 

Vindictive 

Hatred 

Aversion 

Disgust 

Malicious 

Envy 

Cautious 

Timidity 

Ambitious 

Pride 

Reserved 

Shame 

Arrogant 

" 

Servile 

Awe 

Bold 

Exultation 

5.  Socicd 

6.  Instinctive  and  Sentimental 

Attitude 

Emotion 

Attitude 

Basis 

Devoted 

Affection 

Miserly 

Acquiring  instinct 

Friendly 

Cordiality 

(Avaricious) 

Compassionate 

Pity 

Orderly 

Cleanliness 

Attachment  ? 
Loyal            > 

5  Gratitude 
(  Admiration 

Nomadic 

Wandering  instinct 

Antagonistic 

Detestation 

Credulous 

Belief 

Sullen 

Revenge 

Skeptical 

Disbelief 

Distrustful 

Suspicion 

Perplexed 

Doubt 

Supercilious 

Scorn 

Biased 

Belief  and  Disbelief 

in  the  American  Revolution,  and  those  of  the  next  generation 
will  emotionalize  toward  the  several  nations  concerned  in  the 
World  War.  The  killing  of  the  Austrian  archduke  has  been 
described  both  as  a  dastardly  assassination  and  as  a  sublime 
act  of  patriotism.  The  judges  who  sentenced  King  Charies 
are  still  called  '  regicides  '  by  sturdy  British  royalists  —  a 
suggestion  of  the  word  homicide,  with  its  moral  stigma. 
Where  the  narrative  itself  is  unimpeachable  the  choice  of 
adjectives  will  frequently  betray  to  an  acute  observer  the 
writer's  emotional  bias. 
Most  of  our  dispositions,  like  our  emotions,  are  imper- 


340  ATTITUDE  [ch.  xv 

fectly  adjusted  to  the  conditions  of  civilized  life.  If  we  test 
our  attitudes  (or  better  still  the  attitudes  of  others)  by  social 
experience,  we  find  that  the  emotional  element  generally 
hampers  the  intercourse  of  man  with  man.  The  servile  dis- 
position is  as  disconcerting  as  the  arrogant.  There  are  some 
exceptions.  Loyalty,  compassion,  and  the  like  are  disposi- 
tions which  promote  cooperation  among  men  and  assist  the 
socializing  trend  of  human  development.  From  the  peda- 
gogic standpoint  the  early  training  of  emotions  and  dispo- 
sitions seems  even  more  important  than  the  cultivation  of 
motor  habits. 

Appreciation  and  Conscience.  —  Of  the  remaining  attitudes 
the  most  important  are  those  which  develop  out  of  thought 
experiences  and  social  situations.  The  principal  attitudes  in 
these  two  spheres  of  life  are  shown  in  Table  XVI,  together 
with  certain  prominent  attitudes  of  other  sorts. 

A  special  group  of  attitudes  develop  in  connection  with  our 
casual,  ordinary  thinking.  Some  persons  constantly  revert 
to  the  past;  they  live  in  retrospection.  Others  reach  out 
toward  the  future;  they  tend  to  take  the  anticipatory  attitude. 
The  highly  imaginative  mind  assumes  an  imaginative  atti- 
tude; or  this  tendency  may  result  in  desultory  thinking. 

The  attitudes  which  grow  out  of  rational  thinking  may  be 
grouped  together  under  the  head  of  appreciation.  One  of  the 
most  important  of  these  is  the  problem  attitude.'  This 
means  that  when  we  are  given  a  problem  or  a  question  to 
solve  we  tend  to  keep  this  problem  before  us  as  the  basis  of 
our  thinking.  A  succession  of  thoughts  follow,  but  they  all 
relate  to  this  particular  problem.  The  attitude  is  not  the 
particular  problem,  but  the  tendency  to  keep  a  definite  prob- 
lem before  us  and  direct  our  thoughts  with  reference  to  it. 
In  the  case  of  Langley  or  the  Wright  brothers,  the  problem 
thought  was  how  to  devise  a  flying-machine;  the  problem 

*  Also  called  task  or  question  attitude;  the  German  equivalent  Aufgabe 
is  frequently  used  in  English  books. 


CH.  xv]       APPRECIATION,  CONSCIENCE 


341 


Table  XVI. —  EboHER  Human  Attitudes 

1.  Thought  Attitudes 
Attitude  Basis 

(a)  General: 
Retrospective 
Anticipatory 
Desultory,  Imaginative 
Naive 

(b)  Rational  Appreciation: 

Interrogative  (Problem  attitude)  Doubt  (feeling  marginal) 


Memory  coefficient  vivid 
Purpose  (volition  marginal) 
Associative  thought 


Impartial,  Dogmatic 

BeUef  (      "            "       ) 

Interpretive 

Meaning 

Evaluative 

Value 

Esthetic  appreciation 

Esthetic  sentiment  (feeling  marginal) 

Logical  appreciation 

Rational  thought 

Analytic 

"           " 

Synthetic,  Constructive 

«           « 

Critical 

"           " 

Social  and  Moral  Attitudes          3 

.  Other  Secondary  Attitudea 

{Conscience) 

Conciliatory,  Cooperative 

(a)  Volitional  Attitudea  (Proclivities): 

Contrary,  Competitive 

Persevering,  Obstinate 

Inculpatory,  Condemning 

Vacillating 

Laudatory,  Approving 

Judicial 

(b)  Language  Attitudes: 

Receptive 

Self-centered.  Self-satisfied 

Expressive 

Altruistic 

Voluble 

Penitent 

Reticent 

Suppliant 

Forgiving 

(c)  Ideal  Attitudes: 

Prudish 

Idealistic 

Irresponsible 

Practical 

Superstitious  (fetish  and  tabu) 

Sensual 

Duty-boimd  (moral  obligation) 

Scientific 

Artistic 

attitude  enabled  them  to  maintain  this  central  thought  per- 
sistently year  after  year,  or  to  return  to  it  repeatedly,  so  that 
their  thinking  was  ever  on  the  subject  of  human  flight. 

The  interpretive  and  evaluative  attitudes  permeate  our 
perceptual  life  as  well  as  our  thoughts.  We  become  trained 
to  observe  differences  in  kind  and  quantitative  differences 
among  the  objects  that  we  perceive.     An  interpretive  atti- 


S42  ATTITUDE  [ch.  xv 

tude  toward  thought  is  cultivated  by  modern  education. 
Writers  learn  to  appreciate  subtle  distinctions  in  the  mean- 
ing of  words.  Even  the  average  reader  acquires  an  attitude 
toward  individual  words.  James  speaks  of  the  feeling  that 
attaches  to  such  minor  words  as  and,  if,  but,  and  by.  These 
are  really  instances  of  the  appreciative  attitude,  which  leads 
us  to  interpret  or  evaluate  the  relations  of  words  in  a  sentence 
with  as  much  keenness  as  we  interpret  scientific  laws. 

Esthetic  appreciation  is  the  attitude  which  approves  a 
musical  composition  or  a  painting  as  artistically  correct,  or 
condemns  it  on  account  of  faulty  technique.  Logical  appreci- 
ation is  our  thirst  for  logical  accuracy  and  correct  reasoning, 
whether  we  agree  with  the  premises  or  not. 

In  our  relations  to  other  men  and  to  society  at  large  a 
number  of  important  social  attitudes  have  arisen.  A  satis- 
factory classification  of  these  is  difficult,  because  they  shade 
from  emotional  or  volitional  experiences  into  the  sphere  of 
conduct  by  gradual  degrees.  Thus  the  fault-finding  attitude 
contains  a  large  element  of  emotion,  but  is  tinged  with  a  slight 
sense  of  obligation  toward  society;  the  inculpatory  attitude 
of  a  public  prosecutor,  on  the  other  hand,  has  scarcely  any 
emotional  tinge.  Midway  between  these  is  the  accusatory 
attitude  so  frequently  noticed  in  modern  political  and  com- 
munity life. 

The  term  conscience  is  commonly  applied  to  moral  and 
social  attitudes.  It  generally  carries  an  emotional  tinge; 
and  this  is  historically  justified,  because  the  emotions  have 
been  a  powerful  factor  in  developing  our  social  ideals  and 
conduct.  But  the  notion  of  conscience  may  be  extended  to 
such  unemotional  phenomena  as  the  judicial  attitude  and  the 
sense  of  moral  obligation  (the  duty-bound  attitude). 

The  two  attitudes  of  contrariness  and  condemnation  illus- 
trate the  tendency  of  social  and  moral  attitudes  to  become 
fixed  and  generalized.  The  contrary-minded  man  raises 
objections  to  anything  his  friends  suggest.    If  you  propose  a 


CH.  xv]       APPRECIATION,  CONSCIENCE  343 

walk  he  wants  to  stay  at  home.  If  you  order  coffee,  he  orders 
tea.  If  you  suggest  going  to  one  theater  he  prefers  another. 
Any  statement  you  make  he  is  ready  to  challenge.  The 
fault-finder  takes  a  somewhat  similar  attitude  in  the  moral 
sphere.  He  is  forever  picking  flaws  in  the  actions  of  others 
or  in  the  social  order  of  the  community.  "  Why  did  n't 
you  — ,"  and,  "  Will  you  never  learn  — ,"  and,  "  Any  idiot 
would  have  known  better,"  are  typical  of  the  condemning 
attitude.  This  same  attitude  revels  in  denunciation  of  the 
flaws  in  our  social  organization.  When  the  fault-finder  sees 
a  break  in  the  pavement  the  road  commission  is  blamed.  If 
he  sees  newspapers  scattered  about  the  public  parks  he 
berates  our  lack  of  social  breeding. 

Social  and  moral  attitudes  evolve  in  much  the  same  way  in 
all  races,  but  the  situations  which  evoke  them  vary  greatly  in 
different  communities  and  stages  of  civilization.  To  put  it 
the  other  way  round,  the  same  act  or  the  same  objective  situ- 
ation may  yield  very  different  attitudes  in  various  races  and 
culture-stages.  It  depends  upon  the  traditions  and  cus- 
toms of  the  people  whether  the  attitude  of  obligation  is 
assumed  in  a  given  situation  or  not. 

For  example,  in  many  communities  the  child  is  regarded  as 
the  slave  of  his  parents,  who  do  not  recognize  any  obligation 
toward  their  offspring  except  to  feed  and  clothe  them.  In 
other  communities  there  is  recognized  an  obligation  on  the 
part  of  the  parents  to  educate  their  children  and  fit  them  for 
their  life-work. 

Among  the  ancient  Romans  it  was  customary  to  expose 
deformed  and  weak  children  and  let  them  die.  A  similar 
custom  prevails  to-day  among  the  Eskimos.  In  other  socie- 
ties, such  as  our  own,  these  weaklings  are  especially  cared  for 
and  protected. 

The  prvdish  attitude  illustrates  even  more  strikingly  how 
social  attitudes  depend  on  custom.  In  certain  countries  the 
sight  of  a  woman's  unveiled  face  shocks  the  moral  sense. 


344  ATTITUDE  [ch.  xv 

Elsewhere  the  same  shock  is  caused  by  a  skirt  revealing  the 
ankle  or  the  knee. 

Even  the  attitude  toward  fundamental  social  relations, 
such  as  marriage,  varies.  From  the  standpoint  of  ethics  the 
question  of  monogamy  and  polygamy  is  of  prime  importance. 
The  science  of  ethics  seeks  to  determine  which  of  these  two 
conceptions  of  duty  is  higher  and  better.  Psychology  studies 
duty  only  as  a  mental  attitude  —  it  does  not  attempt  to  pass 
judgment  on  its  particular  applications. 

The  attitudes  which  grow  up  in  connection  with  volition, 
language,  and  ideals  are  not  especially  prominent.  Volition 
develops  the  persevering  attitude,  with  its  extreme  limit, 
obstinacy;  in  the  other  direction  it  may  lead  to  vacillation. 
The  use  of  language  results  in  receptive  and  expressive  atti- 
tudes; the  reticent  man  is  inclined  to  listen,  while  the  voluble 
man  insists  that  every  one  else  shall  listen  to  him. 

An  ideal  is  made  up  of  thoughts,  feelings,  and  volitions. 
Because  of  this  complexity  our  ideals  are  seldom  definite, 
concrete  experiences.  But  they  develop  in  the  form  of  deep- 
lying  ideal  attitudes,  which  serve  as  motives  of  action  and  con- 
trol the  course  of  our  lives.  The  idealistic  man,  the  practical 
man,  the  scientist,  and  other  types  are  distinguished  on  the 
basis  of  certain  underlying  attitudes  which  govern  their 
behavior  and  conduct. 

Attitudes  and  Consciousness.  —  Our  attitudes  always  con- 
tribute something  to  our  experiences.  But  usually  the 
material  they  contribute  is  so  obscure  that  it  is  not  observed 
by  the  man  himself  at  the  time;  it  is  subconscious.  In  an 
earlier  chapter  '  we  distinguished  between  subliminal  and 
subordinate  consciousness.  Attitudes  are  generally  sub- 
liminal —  they  are  too  faint  to  be  noticed,  though  they  exert 
a  real  and  usually  a  powerful  influence  on  our  experiences. 

But  the  question  arises,  what  becomes  of  an  attitude  when 
it  b  not  actually  in  use?  Does  it  act  subconsciously  (that 
1  Ch.  vi,  pp.  1S6-1S8. 


CH.  xv]      RELATION  TO  CONSCIOUSNESS  345 

is,  in  a  subordinate  consciousness)  when  it  is  not  working  con- 
sciously? It  seems  probable  that  our  attitudes  do  work  sub- 
consciously at  times,  but  not  often.  An  attitude  is  a  reten- 
tion trace,  only  it  is  cut  far  deeper  than  any  single  memory 
impression.  Memories  are  not  stored  away  in  the  mind;  — 
the  traces  are  there  ready  for  use,  but  they  are  inactive  so 
long  as  they  are  not  actually  used.  And  just  so  with  our 
attitudes.  Usually  they  are  not  active;  they  are  neither  sub- 
liminal nor  are  they  constantly  working  in  a  subordinate  con- 
sciousness. In  fact  all  that  persists  between-times  is  the 
trace  which  makes  the  attitude  possible.  When  the  trace  is 
aroused,  then  the  attitude  appears  as  an  element  in  our  con- 
scious experience. 

Character 

Nature  of  Character.  —  Character  arises  from  the  consoli- 
dation of  attitudes  into  more  permanent  trends  of  life.  Just 
as  the  constant  repetition  of  similar  experiences  leads  to  the 
development  of  fixed  tendencies  called  attitudes,  so  our  atti- 
tudes tend  to  combine  into  deep-lying  general  tendencies. 
A  man's  various  thought  attitudes  are  not  independent, 
because  man  is  an  *  integrated  '  individual,  leading  one  single 
life.  If  your  interest  centers  in  the  study  of  biology,  this 
affects  your  attitude  toward  languages;  you  are  interested  in 
the  classics  because  biological  terms  are  derived  from  Greek 
and  Latin  roots,  or  in  German  on  account  of  the  biological 
works  written  in  that  language.  You  may  be  wholly  unin- 
terested in  Arabic  or  Russian,  because  they  have  only  a  slight 
bearing  on  your  subject.  On  the  other  hand  if  you  are  a 
linguist  you  are  interested  to  some  degree  in  all  languages, 
while  your  interest  in  biology  may  be  limited  to  its  use  of 
Greek  and  Latin  roots. 

The  interworking  of  countless  attitudes  in  each  sphere  of 
mental  life  results  in  building  up  a  *  composite  attitude  '  in 
that  sphere.    Our  thought  and  perception  attitudes  unite  to 


346  CHARACTER  [ch.  xv 

form  a  composite  attitude  toward  this  kind  of  mental  material. 
This  composite  attitude  is  called  our  intellectual  character. 
There  are  four  principal  lines  of  character  development; 
three  correspond  to  the  three  great  varieties  of  sensation  — 
external,  systemic,  and  motor  —  the  fourth  arises  from  our 
social  relations.    These  phases  of  character  are: 

Intellect  (or  intellectuality) 
Temperament 
Skill  (or  skillf  Illness) 
Morality 

The  study  of  character  carries  us  beyond  the  examination 
of  separate  experiences.  We  begin  to  see  the  individual  as  a 
whole,  and  we  can  compare  one  man  with  another.  A  man's 
character  is  his  general  rating  in  one  of  the  four  chief  phases  of 
mental  life.  It  is  the  measure  of  his  mental  capacity  and 
attainment  in  that  phase  of  life. 

Character  is  a  combination  of  many  particular  attitudes. 
Each  separate  attitude  may  be  regarded  as  a  trait  of  char- 
acter; and  in  practice  our  measure  of  a  man's  character  con- 
sists in  rating  each  important  trait.  Each  attitude  or  trait 
manifests  itself  in  concrete  actions,  so  that  practically  we  rate 
a  man's  traits  and  his  character  through  his  responses.  Col- 
lege examinations  are  a  means  for  rating  a  student's  intellec- 
tual character  in  certain  definite  lines.  A  soldier's  behavior 
in  battle  enables  us  to  rate  him  for  courage.  Strictly  speak- 
ing, a  man's  character  is  not  the  rating  which  his  fellows 
actually  give  him;  '  for  such  ratings  are  liable  to  error. 
Character  is  really  the  rating  which  the  man  would  receive  if 
one  could  appraise  him  correctly. 

Intellect.  —  Intellect  is  the  phase  of  character  which  grows 
up  in  connection  with  the  information  received  through  our 
external  senses.  The  impressions  obtained  through  these 
senses  are  especially  apt  to  be  retained,  so  that  our  memories 
and  thoughts  of  the  external  world  play  an  important  part 
^  This  practical  rating  is  a  man's  reputation. 


CH.  xv]  INTELLECT  347 

in  our  lives.  In  rating  a  man's  intellect,  his  ability  to  reason, 
think,  and  remember  counts  more  than  accurate  perception 
and  vivid  imagination. 

Intellectual  development  proceeds  in  two  distinct  direc- 
tions, which  correspond  in  a  figurative  way  to  breadth  and 
height.  The  breadth  of  a  man's  intellect  is  measured  by  the 
number  of  different  traits  that  he  has  developed;  height 
means  the  amount  of  his  growth  in  each  independent  attain- 
ment. The  breadth  of  your  intellect  depends  essentially 
upon  the  complexity  of  your  inherited  nerve  structure,  while 
its  height  depends  more  largely  upon  your  education. 

Both  breadth  and  height  must  be  taken  into  account  in 
rating  a  man's  intellect.  There  are  instances  of  mathemati- 
cal prodigies  and  memory  geniuses  who  in  other  respects  are 
far  below  the  average  mental  level.  And  there  are  men  of 
great  mental  versatility  who  fail  to  measure  up  to  the  aver- 
age in  any  one  particular;  their  minds  are  too  spread-out. 
A  man  of  high-grade  intellect  is  one  whose  attainments  are 
both  broad  and  high. 

Various  attempts  have  been  made  to  measure  intellectual 
attainment.  The  great  difficulty  has  been  to  distinguish  the 
independent  phases  of  intellect  and  to  estimate  their  relative 
importance.  An  important  step  in  this  direction  is  the  scale 
devised  by  Binet  and  Simon  for  measuring  the  mental  growth 
of  children.  This  scale  consists  of  a  large  number  of  tests 
involving  various  mental  processes,  and  so  graded  that  the 
child's  success  in  performing  the  tests  will  indicate  his  gen- 
eral intellectual  level.  For  example,  the  growth  of  memory 
is  tested  by  his  ability  to  repeat  sentences  of  various  lengths 
and  series  of  numbers  of  three,  four,  five,  and  more  figures. 
Rational  thought  is  tested  by  giving  the  child  a  statement 
which  contains  some  absurdity,  and  asking  him  to  point  out 
what  is  wrong  in  it.  There  are  also  tests  involving  simple 
mathematical  problems,  tests  of  practical  judgment,*  tests  to 

*  E.g.,  "What  b  the  thing  for  you  to  do  if  a  playmate  hits  jou  without 


848  CHARACTER  [ch.  xv 

show  the  extent  of  the  child's  vocabulary,  and  many  others. 
In  practice  the  tests  are  arranged  in  order  of  increasing  diffi- 
culty.   Five  tests  cover  each  year  of  mental  growth. 

The  success  of  the  Binet  Scale  as  a  measure  of  intellect  is 
due  to  the  fact  that  the  intellectual  development  of  children 
is  relatively  simple;  they  have  not  yet  developed  a  great 
variety  of  complex  mental  traits.  On  examining  all  the 
children  in  a  large  school  and  comparing  those  of  the  same 
age,  it  is  found  that  fifty  per  cent  of  the  ten-year-old  children 
succeed  in  a  certain  number  of  these  tests.  This  number  is 
taken  as  the  measure  of  the  average  intellectual  level  at  ten 
years.  A  child  of  ten  who  succeeds  in  five  more  tests  than  the 
average  child  of  his  age,  is  one  year  advanced.  Children  of 
ten  years  who  only  attain  the  nine-year  standard  are  said 
to  be  one  year  retarded;  their  *  mental  age '  is  nine  years. 
The  same  procedure  is  used  in  determining  the  standard  for 
each  age. 

In  applying  mental  tests  to  adults  a  difficulty  arises  owing 
to  the  great  individual  differences  in  breadth.  A  man  may  be 
highly  developed  along  certain  lines  and  deficient  in  others. 
It  has  not  yet  been  determined  satisfactorily  how  to  compare 
these  different  attainments  with  one  another  so  as  to  repre- 
sent fairly  the  individual's  mental  level.  The  most  satis- 
factory adult  tests  at  present  are  those  used  during  the  World 
War  in  the  United  States  Army.  The  Army  Alpha  Tests 
were  applied  to  about  1,500,000  recruits  and  officers,  and  are 
believed  to  have  successfully  rated  the  intellectual  standing 
of  these  men.' 

A  mental  scale  for  adults,  to  be  complete,  should  include 
separate  tests  for  each  independent  intellectual  trait.      It 

meaning  to  do  it?"  This  is  answered  correctly  by  the  average  child  of 
eight  years. 

^  The  Binet,  Alpha,  and  other  tests  of  this  sort  are  usually  called  '  intelli- 
gence tests.'  In  point  of  fact  most  of  them  measure  only  intelleotual  devel- 
opment —  not  skill,  morality,  or  temperament.  An  animal  maze  test  would 
measure  motor  intelligence,  or  skill. 


CH.  xv]  INTELLECT  349 

should  distinguish  also  between  traits  that  have  been  devel- 
oped by  special  training  or  schooling,  and  those  that  grow  up 
under  the  ordinary  influences  of  social  environment.  The 
latter  seem  to  deserve  a  higher  rating.  Mere  scholarship 
and  information  do  not  denote  so  high  a  degree  of  intellectual 
development  as  the  less  cultivable  processes  which  underlie 
them. 

Mental  tests  differ  from  school  or  college  examinations  in 
just  this.  An  examination  in  any  subject  brings  out  merely 
the  training  which  the  student  has  had  in  that  particular  hue; 
it  indicates  only  in  a  general  way  his  degree  of  mental  devel- 
opment. A  dull  person  will  stand  low  no  matter  how  much 
drill  he  has  had  in  the  subject;  but  except  in  this  crude  way 
examinations  do  not  indicate  a  person's  general  mental  fitness. 
Entrance  examinations  do  not  show  whether  the  student  is 
mentally  fitted  to  pursue  the  college  course.  Entrance  tests, 
if  well  selected,  determine  just  this  point,  which  is  of  prime 
importance  in  picking  out  suitable  students. 

In  applying  mental  tests  special  care  should  be  taken  that 
the  results  are  truly  representative.  If  the  individual  tested 
has  been  *  coached,'  his  answer  to  a  question  supposed  to 
involve  reasoning  may  be  really  a  feat  of  memory.  A  phono- 
graph, supplied  with  the  proper  record,  might  pass  a  very 
advanced  test  and  give  results  indicating  a  superlative  degree 
of  intellect.  Such  a  result  would  measure  the  intellectual 
grade  of  the  individual  who  prepared  the  record  —  not  the 
intellect  of  the  phonograph  itself.  Unless  due  care  is  taken 
in  giving  a  mental  test  (or  a  college  examination  for  that 
matter),  the  results  may  indicate  the  intellect  of  the  '  coach  ' 
—  not  the  mental  level  of  the  testee. 

A  question  which  interests  psychologists  at  present  is 
whether  there  is  such  a  thing  as  general  intellectual  training: 
Does  training  in  any  special  line  (mathematics,  classics, 
science)  result  in  all-round  intellectual  improvement?  Or  is 
the  improvement  limited  to  the  trait  that  is  being  trained? 


350  CHARACTER  [ch.  xv 

The  answer  is  not  yet  clear.  The  weight  of  evidence  at 
present  seems  to  indicate  that  training  is  '  specific,'  not  gen- 
eral. To  the  extent  that  two  mental  traits  have  a  common 
factor,  training  in  one  does  improve  the  other.  But  there 
does  not  appear  to  be  a  factor  of  general  intelligence.  Gen- 
eral intelligence  is  a  combination  of  many  distinct  traits. 

Temperament.  —  Temperament  is  the  phase  of  character 
which  develops  out  of  our  desires  and  emotional  attitudes. 
It  is  the  permanent  cast  of  our  systemic  life.  In  general  a 
man's  temperament  develops  quite  independently  of  his 
intellect.  To  say  that  a  man  is  phlegmatic  tells  us  nothing  at 
all  about  his  intellectual  capacity. 

The  reason  why  these  two  phases  of  character  are  inde- 
pendent is  not  difficult  to  understand.  Intellect  depends 
on  external  stimuli,  temperament  on  stimuli  which  arise 
from  the  operation  of  our  inner  organs  and  glands.  These 
two  sets  of  sensory  nerves  lead  to  different  brain  centers, 
which  are  not  closely  related.  Chronic  indigestion,  over- 
development of  one  of  the  ductless  glands,  oversensitivity  to 
pain,  or  any  other  particular  internal  condition  will  affect  our 
systemic  experiences;  this  may  modify  our  temperamental 
character  more  or  less  profoundly,  but  it  exerts  only  a  slight 
influence  upon  our  intellectual  growth.  What  we  see  and 
hear  serve  to  develop  our  intellect,  but  these  experiences  of 
the  outer  world  affect  our  temperament  only  to  a  slight 
degree.  These  two  sides  of  human  character  develop  each 
in  its  own  way.  We  rate  a  man's  temperament  in  altogether 
different  terms  from  his  intellect. 

The  ancients  recognized  four  kinds  of  temperament,  the 
choleric,  melancholic,  sanguine,  and  phlegmatic.  This  classi- 
fication was  based  upon  a  doctrine  of  internal  secretions  which, 
though  in  the  main  erroneous,  contained  a  germ  of  truth. 

Temperament  is  possibly  correlated  with  the  modes  of 
heart  action.  The  heart-beat  may  be  strong  or  weak,  and 
it  may  be  rapid  or  slow.    Combining  these  pairs  we  get  four 


CH.  xv]  TEMPERAMENT  351 

varieties  of  temperament,  which  correspond  to  the  classic 
types.  But  this  does  not  take  into  account  the  distinction 
between  pleasant  and  unpleasant  feeling,  which  is  really  the 
most  significant  characteristic  of  systemic  sensations. 

A  more  natural  classification  is  based  on  both  the  type  of 
activity  and  the  quality  of  feeling.  The  motor  side  has  two 
phases,  active  and  passive;  the  feeling  element  three  phases, 
pleasant,  unpleasant,  and  indifferent.  Combining  these  two 
groups  of  characteristics  we  obtain  six  varieties  of  tempera- 
ment.    [Table  XVII.] 

Table  XVU.  —  Classification  of  Tempebamentb 
Motor  Phase  Feeling  Tone  Temperament 

5  Pleasant  Sanguine 

Unpleasant  Choleric 

Indifferent  Mercurial 

Passive  •< 

While  temperament  is  not  so  important  a  factor  in  life  as 
intellect  or  the  other  phases  of  character,  it  should  not  be 
overlooked  in  our  study  of  the  mind,  nor  yet  in  education. 
The  choleric  and  to  some  extent  the  melancholic  tempera- 
ment are  a  practical  handicap  in  meeting  the  situations  which 
confront  us  in  social  life.  People  do  not  relish  having  inti- 
mate relations  with  a  man  who  is  hop)elessly  addicted  to 
violent  emotions  of  the  unpleasant  type  —  nor  yet  with  one 
who  is  perennially  grim  and  sour.  It  is  up  to  the  parent  and 
teacher  to  train  the  child  away  from  these  unsocial  trends,  so 
far  as  education  is  capable  of  molding  the  temperament. 

Systemic  stimuli  come  from  the  glands  and  from  the 
internal  organs  controlled  by  the  autonomic  nervous  system. 
The  autonomic  system  works  somewhat  independently  of 
voluntary  control;  but  it  has  connections  with  the  central 
nervous  system.  Our  thoughts  affect  our  digestion  and 
secretions.     By  deliberately  cultivating  cheerful  attitudes. 


Pleasant 

Jovial 

Unpleasant 

Melancholic 

Indifferent 

Phlegmatic 

352  CHARACTER  [ch.  xv 

we  can  develop  a  cheerful  temperament.  A  similar  influence 
is  exerted  by  social  example  and  systematic  education. 

These  influences  do  not  entirely  solve  the  problem.  The 
real  solution  is  to  train  our  internal  organs  to  work  properly. 
This  is  partly  the  task  of  the  physician.  Whether  by  drugs 
or  by  diet  or  by  baths  and  other  agencies,  it  lies  within  his 
power  to  modify  the  temperament  to  a  far  greater  extent 
than  can  be  accomplished  through  the  central  nervous  sys- 
tem. The  individual  himself  can  cooperate  here  and  in  many 
cases  can  accomplish  the  results  alone.  Regular  habits  of 
eating,  plenty  of  physical  exercise,  a  proper  amount  of  sleep, 
will  keep  the  normal  body  in  good  working  order  and  develop 
the  temperament  in  the  right  direction. 

Skill.  —  Skill  is  the  phase  of  character  which  develops  out 
of  our  motor  attitudes  and  habits.  It  is  the  permanent  mold- 
ing of  our  '  response  '  life.  A  man's  motor  character  is  rated 
according  to  the  effectiveness  of  his  muscular  activity;  and 
this  rating  is  distinct  from  the  measure  of  his  intellect  and 
temperament.  Like  intellect,  skill  develops  in  two  dimen- 
sions: breadth  and  height.  The  breadth  of  skill  is  measured 
by  the  number  of  independent  motor  acts  that  the  individual 
can  perform.  Its  height  is  the  degree  of  success  in  perform- 
ance. 

The  remarkable  breadth  of  motor  development  in  civilized 
man  will  be  realized  if  we  attempt  to  make  a  list  of  the  com- 
mon acts  of  modern  life.  The  catalogue  would  include  such 
varied  acts  as  eating,  moving  about,  dressing,  writing,  draw- 
ing, conversing,  playing  games,  and  a  host  of  other  perform- 
ances. Besides  these  common  activities  each  trade  and 
technical  profession  has  its  own  particular  motor  program. 
In  comparing  the  motor  character  of  individuals,  and  in 
fating  the  comparative  development  of  various  races,  breadth 
of  skill  is  an  important  factor  to  consider. 

On  the  other  hand,  height  —  the  man's  degree  of  success  in 
performing  any  particular  kind  of  act  —  furnishes  a  more  ade- 


CH.  xv]  SKILL  858 

quate  index  to  skill.  In  determining  height  of  motor  attain- 
ment two  separate  factors  must  usually  be  measured :  speed 
and  accuracy  (eh.  xi).  In  tests  of  skill  we  seek  to  determine 
(1)  the  time  required  to  perform  the  act,  and  (2)  the  mmiber 
of  errors  made,  or  amount  of  inaccuracy. 

It  is  often  difficult  to  estimate  the  relative  value  that 
should  be  assigned  to  these  two  factors.  In  certain  kinds  of 
work  accuracy  or  precision  is  of  far  greater  importance  thiin 
speed;  in  other  cases  the  opposite  is  true.  A  telescope  lens 
must  be  ground  to  the  utmost  limit  of  accuracy,  regardless  of 
time  expended.  A  ready-made  garment  on  the  other  hand 
must  be  finished  quickly,  in  order  to  reduce  the  cost  of  pro- 
duction; irregularities  in  the  cutting  are  taken  as  a  matter  of 
course. 

Sometimes  the  conditions  are  such  that  speed  and  accuracy 
are  combined  into  a  single  factor.  In  a  certain  tapping  test 
the  individual  is  required  to  insert  a  plug  into  a  series  of  holes 
in  succession,  and  to  do  it  as  rapidly  as  possible.  Each  inser- 
tion produces  an  electric  contact  and  makes  an  audible  click. 
If  the  subject  misses  the  hole  at  first  he  must  correct  the  error 
before  proceeding  to  the  next  hole.  Here  the  inaccuracy 
factor  is  eliminated  entirely,  and  speed  is  the  only  variable  to 
be  measured. 

A  scale  of  skill,  like  the  scale  of  intellect,  should  include  a 
great  variety  of  typical  acts  of  various  sorts,  if  it  is  to  indicate 
breadth  as  well  as  height  of  attainment.  Up  to  the  present 
the  construction  of  a  measuring  scale  for  skill  has  not  pro- 
gressed so  far  as  the  scale  for  intellect.  The  importance  of 
intellect  seems  to  have  been  somewhat  overemphasized  in 
modern  civilization.  We  are  only  beginning  to  recognize 
that  skill  is  an  essential  phase  of  human  character. 

The  education  of  skill  belongs  largely  to  technical  schools 
and  institutions  for  manual  training.  But  some  progress 
can  be  made  at  home.  Boys  should  be  taught  to  drive  nails, 
saw  straight,  and  perform  the  common  motor  activities  of 


354  CHARACTER  [ch.  xv 

every-day  life  with  accuracy.  The  home  training  of  girls  in 
the  household  arts  is  more  advanced,  though  it  still  leaves 
much  to  be  desired. 

Games  of  skill,  such  as  baseball,  billiards,  golf,  and  tennis, 
furnish  good  training  in  the  fundamentals  of  motor  accuracy. 
A  general  system  of  motor  education,  corresponding  to  the 
intellectual  education  of  our  primary  and  secondary  schools, 
remains  to  be  developed.  It  is  one  of  the  great  tasks  of  the 
present-day  educator. 

Morality.  —  Morality  is  the  phase  of  character  which  con- 
cerns a  man's  relations  to  his  fellows.  It  depends  upon  our 
family  and  social  life.  There  are  no  separate  receptors  or 
senses  for  social  stimuli.  All  our  information  regarding  our 
fellow  men  is  received  through  the  external  senses  of  sight, 
hearing,  touch,  and  the  rest. 

Owing  to  the  peculiar  relations  in  which  human  beings 
stand  toward  one  another,  our  perception  of  other  persons 
arouses  within  us  certain  special  kinds  of  emotions  and  senti- 
ments, and  leads  to  social  responses.  If  you  soothe  a  sick 
child,  or  give  a  coin  to  a  beggar,  or  rescue  a  drowning  man, 
the  act  is  due  to  a  social  feeling  within  you.  Your  plunge  into 
the  river  to  save  a  man  is  a  different  sort  of  act,  mentally 
speaking,  from  the  plunge  you  take  for  mere  pleasure,  though 
the  muscular  activity  in  the  two  cases  may  be  similar.  In  a 
word,  our  social  relations  develop  social  attitudes,  and  these 
attitudes  develop  a  new  phase  of  human  character,  called 
moral  character  or  morality.  So  important  is  this  side  of  our 
mental  life  that  in  popular  language  the  word  character  is 
often  equivalent  to  moral  character. 

Moral  character,  like  intellect  and  skill,  develops  in  two 
dimensions:  breadth  and  height.  Our  range  of  social  rela- 
tions extends  gradually  with  the  progress  of  civilization.  It 
includes  two  separate  fields :  the  family,  and  the  tribe  or  social 
group.  Family  relations  include  several  sorts:  marital, 
parental,  fraternal,  and  filial,  each  of  which  involves  a  num- 


CH.  xv]  MORALITY  355 

ber  of  separate  duties.  Community  life  gives  rise  to  many 
relations  with  corresponding  duties :  friendship,  business  and 
other  economic  dealings,  community  organization,  and  the 
general  relationship  of  man  to  man.  As  civilization  devel- 
ops and  the  social  organization  is  perfected  these  relations  are 
extended,  giving  rise  to  broader  relations  and  duties  —  toward 
our  country,  our  race,  and  mankind. 

More  significant  than  the  range  or  breadth  of  social  rela- 
tions is  the  degree  to  which  an  individual  enters  into  these 
relations.  The  height  of  a  man's  moral  character  is  measured 
by  the  extent  to  which  his  social  ideals  and  acts  tend  to  bene- 
fit his  fellows  and  avoid  doing  them  injury. 

Social  behavior  is  called  conduct.  A  man's  moral  character 
is  measured  practically  by  his  conduct  —  by  what  he  does 
and  what  he  neglects  to  do.  The  rating  is  not  determined  by 
what  one  actually  accomplishes  but  by  what  he  intends  to 
accomplish.  The  psychologist  and  moralist  measure  conduct 
in  terms  of  the  man's  motives,  not  in  terms  of  the  motor 
result.  When  you  give  a  dollar  to  a  beggar  you  may  actually 
start  him  on  a  debauch  or  help  to  settle  him  in  a  life  of  idle- 
ness and  uselessness;  yet  the  motive  of  the  gift  may  be  thor- 
oughly good.  It  is  this  that  makes  the  true  rating  of  moral 
character  particularly  difficult.  A  scale  of  morality  must 
take  into  account  not  merely  a  man's  explicit  conduct,  but 
the  attitude  underlying  his  actions;  and  this  involves  a 
determination  of  his  social  thoughts,  emotions,  and  senti- 
ments. 

Religious  conduct  and  character  are  closely  related  to  the 
social.  The  religious  side  of  man's  nature  is  a  striving  to 
propitiate  some  higher  being  or  beings,  to  be  guided  by  an 
all-powerful  and  all-wise  personality,  to  commune  with  God. 
Religious  rites  and  practices  belong  to  the  same  phase  of 
mental  life  as  social  conduct;  religious  attitudes  develop  in 
much  the  same  way  as  social  attitudes.  The  code  of  ethics 
differs  from  the  religious  code,  but  the  mental  basis  of  the 


856  CHARACTER  [ch.  xv 

two  is  the  same.  Man's  religious  character  develops  with 
his  social  growth  rather  than  with  his  intellect  or  tempera- 
ment. 

Moral  character  is  quite  susceptible  to  social  training.  The 
child  starts  life  with  an  inherited  social  tendency;  he  also 
inherits  very  pronounced  self-preservative  tendencies  which 
often  conflict  with  social  ideals.  The  first  duty  of  moral  edu- 
cation is  to  foster  the  child's  social  trend  and  repress  his  self- 
seeking  tendencies. 

But  this  is  not  all.  The  child  at  the  outset  is  quite  ignorant 
as  to  what  acts  are  moral  and  what  are  immoral.  Left  to 
himself  he  may  work  out  the  fundamental  distinctions  in 
the  course  of  time.  The  function  of  moral  education  is  to 
shorten  the  learning  period,  and  to  instill  in  the  child  many 
social  customs,  some  of  which  rest  on  convention  rather  than 
on  natural  human  relations.  He  is  taught  to  speak  the  truth, 
not  to  take  the  property  of  others,  to  say  he  is  sorry  when  he 
has  unwittingly  done  wrong.  The  conventions  of  decency 
and  politeness  are  pointed  out  to  him  concretely  before  he  is 
old  enough  to  appreciate  their  meaning  or  place  in  life.  The 
tendency  of  the  human  mind  to  generalize  helps  the  learning 
process  immensely.  A  few  instances  are  usually  sufficient  to 
teach  the  child  what  society  expects  of  him  in  any  given  sort 
of  situation. 

The  responsibility  for  moral  training  rests  largely  with  the 
parents;  for  the  home  life  presents  a  vastly  greater  variety 
of  social  relations  and  far  more  opportunities  for  moral  or 
immoral  conduct  than  are  found  at  school. 

Reward  and  Punishment.  —  Character  training  in  all 
phases  of  character  is  partly  a  matter  of  natural  mental 
growth,  partly  a  matter  of  example  and  education.  The 
incentive  of  reward  and  the  deterrent  effect  of  punishment 
have  always  been  extensively  used  in  education.  Rightly 
handled  these  two  instruments  are  very  effective  in  speeding 
up  the  training.     A  word  of  praise  when  the  child  has  mas- 


CH.  xv]        REWARD  AND  PUNISHMENT  867 

tered  an  intellectual  problem  or  controlled  his  temper,  serves 
to  fix  the  successful  response;  a  word  of  disapprobation  often 
obviates  a  repetition  of  some  wrong-doing. 

The  danger  in  the  use  of  reward  and  punishment  as  a 
method  of  training  children  lies  in  a  wrong  conception  of  their 
psychological  meaning.  We  must  look  upon  them  solely  as 
means  for  developing  the  child's  character.  The  old  notion  of 
punishment  was  that  when  a  child  makes  a  misstep  he  must 
pay  a  penalty  for  his  error.  Psychologically  this  idea  is  all 
wrong.  The  child  has  only  limited  experience;  his  mental 
powers  are  undeveloped.  It  is  to  be  expected  that  he  will  fail 
more  often  than  he  will  succeed,  whether  in  intellectual  prob- 
lems, in  temperamental  demeanor,  in  problems  of  skill,  or  in 
moral  acts.  To  make  him  sufifer  for  these  failures  is  wretched 
pedagogy.  He  needs  assistance,  not  reprobation.  But  the 
inhibitive  power  of  pain  and  discomfort  is  strong.  If  the 
child  cannot  make  the  proper  nervous  and  mental  adjust- 
ments without  a  pain  incentive,  the  use  of  punishment  is 
justified.  An  admonition  or  a  whipping  clinches  the  warn- 
ing and  often  prevents  a  repetition  of  the  same  mistake. 
The  danger  in  applying  this  method  too  frequently  is  that  the 
child  may  come  to  regard  the  parent  and  teacher  as  an  agent 
for  retribution  instead  of  a  guide.  Punishment  of  any  sort 
should  be  used  sparingly  and  only  when  other  means  of  train- 
ing have  failed. 

The  use  of  reward  has  its  dangers  also.  It  may  serve  to 
make  the  child  careless,  or  he  may  strive  for  the  reward  itself, 
instead  of  aiming  for  successful  development,  which  is  the 
only  psychological  justification  for  rewards.  This  is  true 
even  in  later  life.  Not  infrequently  the  college  educator 
finds  his  students  inquiring  whether  their  grades  are  high 
enough  to  qualify  them  for  Phi  Beta  Kappa.  The  question 
shows  that  they  are  working  for  the  symbol  of  success  —  not 
for  the  mental  attainment  itself.  Rewards  should  perhaps 
be  used  merely  as  a  counterbalance  to  punishments.     If  a 


358  CHARACTER  [ch.  xv 

child  needs  no  punishment  he  probably  needs  no  reward  — 
except  of  course  the  expression  of  friendly  sympathy,  in- 
terest, and  comradeship  on  the  part  of  his  parents  and 
teachers. 

Summary.  —  Experiences  leave  traces,  and  these  traces 
tend  to  consolidate  into  permanent  mental  conditions.  The 
first  step  in  this  process  is  the  development  of  attitudes,  due 
to  the  frequent  repetition  of  similar  experiences.  The  funda- 
mental attitudes  are  interest,  desire,  and  attention,  which  grow 
out  of  external,  systemic,  and  motor  experiences  respectively. 
Among  the  complex  attitudes,  the  dispositions,  based  on  our 
emotional  life,  are  most  significant. 

Attitudes  consolidate  into  more  general  trends  called 
phases  of  character.  The  attitudes  which  grow  out  of  external 
experiences  enter  into  our  intellectual  character  or  intellect; 
systemic  attitudes  build  up  our  temperament;  motor  attitudes 
regulate  our  skill;  social  relations  build  up  a  fourth  phase  of 
character,  called  morality.  All  these  are  subject  to  growth, 
and  except  in  the  case  of  temperament  they  develop  in  two 
dimensions:  height  and  breadth.  Mental  scales  serve  to 
measure  a  person's  mental  development  in  comparison  with 
other  individuals.  The  intellectual  phase  of  character  has 
been  most  successfully  measured. 

Practical  Exercises: 

75.  Compare  the  direct  effect  of  the  stimulus  and  the  influence  of  your 
attitude  in  reading  a  novel,  in  watching  a  ball  game,  in  discussing  some 
question  with  a  friend. 

76.  Analyze  the  attitude  of  pique  ('being  peeved')  in  yourself  and  others, 
including  its  characteristic  manifestations;  also  the  jealous  and  cau- 
tious attitudes. 

77.  Examine  the  report  of  some  important  congressional  or  legislative 
debate;  determine  to  what  extent  the  attitude  of  the  participants  was 
conciliatory,  accusatory,  and  judicial. 

78.  Test  children  from  four  to  twelve  years  old  for  the  number  of  figures 
and  words  (syllables)  which  they  can  repeat  successively  after  one 
hearing.     Report  the  progress  according  to  age. 

79.  Analyze  your  temperament,  and  compare  it  with  that  of  some  intimate 
friend. 


CH.  xv]  SUMMARY  859 

80.  Examine  what  has  been  the  effect  of  punishment  and  reward  on  your 
mental  and  moral  development. 

References: 
On  attention  and  interest:  W.  B.  Pillsbury,  Attention;  F.  Arnold,  Attention 

and  Interest. 
On  temperament:  J.  Jastrow,  Temperament  and  Character. 
On  mental  tests:   L.   M.  Terman,  Measurement  of  Intelligence;  R.  M. 

Yerkes  (ed.),  'Psychological  Examination  in  the  U.S.  Army'  {Trans. 

Nat.  Acad,  of  Sci.,  vol.  15);  G.  M.  Whipple,  Manual  of  Mental  and 

Physical  Tests  (2  vols.) ;  Pintner  and  Patterson,  A  Scale  of  Performance 

Tests. 


CHAPTER  XVI 
PERSONALITY  AND  CONTROL 

Nature  of  Personality.  —  Personality  is  the  entire  mental 
organization  of  a  human  being  at  any  stage  of  his  develop- 
ment. It  embraces  all  four  phases  of  human  character: 
intellect,  temperament,  skill,  and  morality,  and  every  atti- 
tude that  has  been  built  up  in  the  course  of  one's  life. 

Stimuli  are  constantly  pouring  in  upon  you;  in  a  broader 
way,  situations  are  constantly  affecting  you.  How  do  you 
*  take  '  them?  Your  behavior  is  the  joint  product  of  (1)  the 
nerve  impulses  that  penetrate  to  your  centers  and  (2)  your 
entire  mental  organization.  This  second  factor  is  your  per- 
sonality. 

Personality  is  not  inborn  and  unchangeable.  It  is  a 
gradual  growth.  We  are  very  different  persons  at  five,  at 
fifteen,  and  at  twenty-five.  The  difference  is  due  to  the  fact 
that  we  are  all  the  time  gathering  in  new  experiences  and 
assimilating  them.  The  ground-work  of  personality  is  inher- 
ited. Every  creature  inherits  a  nervous  system  of  a  certain 
type,  with  certain  possibilities  and  certain  limitations.  The 
brain  and  nervous  system  of  the  lower  species  are  too  simple 
to  permit  the  development  of  language  or  thought.  The 
normal  human  being  is  born  with  a  complex  and  plastic 
brain,  so  that  he  is  capable  of  learning  to  speak  and  think. 
Given  the  right  sort  of  nervous  system  to  start  with,  the 
power  of  speech  and  thought  is  developed  through  repeated 
experiences.  Our  personality  is  broadened  or  heightened  as 
each  new  sort  of  experience  is  acquired;  it  continues  to  grow 
and  expand  throughout  our  lifetime. 

It  is  more  diflScult  to  rate  a  man's  personality  correctly 
than  to  measure  any  single  trait  or  any  phase  of  his  char- 


CH.  xvi]        NATURE  OF  PERSONALITY  861 

acter.  You  think  you  have  sized  up  a  certain  friend  of  yours 
pretty  accurately.  A  crisis  brings  to  light  some  unsuspected 
strength  or  weakness.  The  retiring,  timid  fellow  shows  a 
grit,  a  perseverance,  a  boldness  perhaps,  with  which  you 
never  credited  him.  The  steady,  masterful  man  suddenly 
goes  off  the  handle.  Why?  Because  of  some  streak  in  his 
personality  which  has  not  hitherto  been  connected  up  with 
his  '  general  self.' 

If  personality  were  merely  intellect  —  or  any  other  special 
character  —  it  would  not  be  difficult  to  determine  a  man's 
future  development  at  the  age  of  twenty.  But  our  contest 
with  the  environment  often  takes  unexpected  turns,  which 
call  into  play  every  side  of  character.  Our  temperament 
influences  our  intellectual  growth  and  our  moral  develop- 
ment. They  may  work  together  or  at  cross-purpKJses.  .^A.'^V^"'^ 
critical  situation  may  find  the  ^^^t.spof«i  our  armor;  V)r  a 
combination  of /ortainate  Mrcumstauces  may  develop  strength 
in  every  part  of  our  equipment  and  malceiia  conquerors.  A 
well-rounded  personalitj*}is  one  that  ei^bles  us  to  cope  with 
all  the  usual  situations  in  life.  OverdevelojMnent  iA.  wne' 
direction  may  be  as  disastrous  ab  underdevelopment.    ' 

Attempts  to^  measure  human  jterspH^ity  scientifigally  have 
met  with  little  success.  Most  of  the  essays  aid  books  on 
personaUty  ^re  written  by  amateur  psychologists,  who  have 
no  appreciation  of  the  real  problems  involved.  They  em- 
phasize certain  striking  individiuil  features,  or  deal  merely 
with  a  few  distinctive  traits  of  character.  The  trained  psy- 
chologist is  apt  to  shirk  the  problem  altogether.  There  is  an 
excellent  reason  for  this.  Before  we  can  measure  person- 
ality we  must  determine  the  relative  importance  of  the  dis- 
tinct phases  of  character  that  make  up  personality.  This  is  a 
difficult  task.  In  a  general  measure  of  human  mentality 
what  proportion  should  be  assigned  to  intellect?  How  much 
should  temperament,  skill,  and  morality  count?  The  only 
satisfactory  solution,  apparently,  is  to  value  each  factor 


362  PERSONALITY  AND  CONTROL      [ch.  xvi 

according  as  it  assists  in  adapting  our  behavior  and  mental 
organization  to  the  external  conditions  of  life. 

Personal  Identity  and  Multiple  Personality.  —  In  normal 
human  beings,  the  whole  mental  life  is  organized  into  one 
continuous  chain  of  complex  experiences.  The  greater  part 
of  your  past  experiences  may  be  brought  into  relation  with 
the  present  if  the  proper  nerve  connections  are  made.  Your 
conscious  life  stretches  back  as  far  as  you  can  rememoer,  and 
every  event  that  you  recall  is  felt  to  belong  to  one  and  the 
same  self.  Your  present  thoughts  and  feelings  and  activi- 
ties are  tinged  with  a  scarcely  describable  element  which  may 
be  called  a  "  sense  of  ownership  ";  they  belong  to  you. 

This  sense  of  the  me  and  mine  is  your  experience  of  personal 
identity.  The  feeling  of  personal  identity  arises  from  the  fact 
that  ordinarily  the  whole  mass  of  an  individual's  experiences 
belong  to  one  continuous  series;  his  mental  Ufe,  though  com- 
plex and  intricate,  is  a  unity. 

In  certain  cases  this  unity  of  self  is  broken.  Groups  of 
experiences  may  be  dissociated  from  the  general  mass  and 
organized  into  a  more  or  less  definite  personality  of  their  own. 
This  happens  most  noticeably  in  disorders  of  the  central 
nervous  system,  such  as  hysteria.  But  there  are  also  cases 
in  normal  life.  Many  of  our  subconscious  mental  processes 
are  *  split-off  '  experiences. 

When  you  carry  on  two  acts  at  once,  such  as  eating  dinner 
and  making  plans  for  the  next  day,  or  knitting  and  talking, 
the  two  activities  are  probably  controlled  by  two  separate 
systems  of  mental  organization.  Individuals  susceptible  to 
trance  or  hypnosis  may  be  absorbed  in  conversation  and  at 
the  same  time  may  write  automatically  on  some  entirely 
different  topic  without  knowing  it.  When  we  have  planned 
out  beforehand  the  itinerary  of  a  walk  and  carry  out  our  pro- 
gram without  thought,  the  succession  of  actions  is  probably 
controlled  by  a  subconscious  organization.  These  are  typi- 
cal cases  of  subordinate  consciousness  or  secondary  'personality. 


CH.  xvi]  PERSONAL  IDENTITY  363 

There  are  occasionally  pathological  instances  where  the 
secondary  personality  becomes  so  completely  organized  as  to 
form  a  separate  self.  This  is  called  co-consciousness  or  diud 
personality.  The  secondary  self  has  developed  into  a  coordi- 
nate primary  self.  The  patient  leads  two  distinct  lives,  one 
alternating  with  the  other.  Sometimes  in  one  state  he  has 
no  memory  of  his  experiences  and  doings  in  the  other  state; 
or  state  A  may  be  remembered  in  state  B,  but  not  the  reverse. 
The  temperament  and  moral  character  of  the  two  personali- 
ties may  be  quite  different.  Pierre  Janet  and  Morton  Prince 
have  studied  cases  in  which  three  or  more  alternating  per- 
sonalities —  all  strikingly  different  —  appear  in  the  same 
person. 

There  is  something  fascinating  to  most  of  us  in  the  study  of 
these  unusual  phenomena.  The  casual  observer  regards  them 
as  weird  and  uncanny  —  perhaps  as  demon-possession  or 
manifestations  of  a  mysterious  spirit-world.  To  the  student 
of  psychology  all  these  instances,  whether  of  secondary  per- 
sonality or  of  dual  personality,  serve  to  emphasize  the  general 
unity  of  the  self.  Multiple  personality  is  the  exception.  In 
most  persons  experiences  are  woven  together  and  organized 
into  one  single  personality. 

The  Notion  of  Self.  —  Our  self-notion  arises  in  connection 
with  this  unity  of  personality.  It  grows  out  of  sensations 
esp)ecially  connected  with  our  body.  The  child  perceives  his 
own  body  through  the  external  senses,  and  he  has  a  mass  of 
organized  systemic  and  motor  sensations  from  within  the 
body.  All  the  sensations  and  ideas  which  refer  to  his  own 
body  and  its  activities  combine  into  a  general  self-perception 
or  self-feeling.  This  is  not  a  *  notion  '  but  a  sensory  experi- 
ence. 

As  thought  and  language  develop  in  the  child,  a  name  is 
attached  to  this  self-feeling.  At  first  the  child  calls  himseU 
*  Baby,'  or  uses  his  own  name:  "  Jack  is  hungry  ";  "  Show  it 
to  Baby."     His  own  personality  stands  on  the  same  footing 


>if: 


364  PERSONALITY  AND  CONTROL      [ch.  xvi 

as  that  of  other  human  beings.  This  first  step  toward  the 
self-notion  may  be  called  the  objective  stage. 

When  the  child  learns  to  use  pronouns  (you,  I,  he)  the 
notion  of  self  becomes  sharply  distinguished  from  the  general 
notion  of  '  human  beings.'  This  second  step  is  the  subjective 
stage;  the  child  has  begun  to  recognize  the  special  relation  of 
his  own  body  and  its  activities  to  his  own  conscious  experi- 
ences. The  true  self-notion  dates  from  this  stage.  It  devel- 
ops constantly  throughout  life,  especially  among  civilized  and 
reflective  beings. 

Finally,  the  child  discovers  a  personality,  with  experiences 
like  his  own,  in  other  human  beings;  he  even  reads  it  into 
lower  animals  and  inanimate  objects.  The  child  punishes 
the  naughty  chair  that  tipped  him  out;  older  people  treat  a 
dog  as  if  he  could  reason.  This  ejection  of  our  self-experiences 
into  others  is  a  third  stage  in  the  growth  of  the  self -notion. 

The  notion  of  self  is  not  a  special,  higher  stage  of  mental 
development,  as  is  commonly  imagined.  Self-consciousness  ' 
runs  through  all  stages  of  mental  growth,  but  it  only  begins  to 
acquire  distinctness  when  language  and  thought  appear,  and 
the  difference  between  I  and  you  comes  to  be  recognized. 

General  Problems  of  Personality.  —  In  studying  any 
science  we  necessarily  proceed  in  a  piecemeal  way.  Each 
element  and  factor  must  be  examined  separately  before  we 
can  attempt  to  study  their  mutual  relations  or  their  bearing 
on  the  whole  subject.  This  is  especially  true  of  psychology. 
First  we  study  the  nervous  system,  then  the  various  senses 
which  furnish  the  material  out  of  which  our  experiences  are 
formed.  Then  we  examine  one  by  one  the  various  kinds  of 
experiences  and  types  of  behavior.  The  real  study  of  mental 
life  begins  when  we  examine  the  succession  of  experiences  and 
the  principles  of  their  connection.     Finally  we  investigate 

^  Self-consciousness  in  psychology  means  consciousness  of  our  own  person- 
ality; this  meaning  should  not  be  confused  with  the  popular  use  of  the  term, 
to  denote  embarrassment. 


■Y  i 


CH.  xvi]       PROBLEMS  OF  PERSONALITY  365 

the  permanent  mental  conditions  which  mold  our  mental 
life  into  an  enduring  self.  Our  attitudes  grow  up  out  of  single 
experiences,  constantly  repeated;  the  consolidation  of  similar 
attitudes  results  in  the  organization  of  our  several  character- 
phases;  and  the  final  outcome  is  our  personality  or  self, 
which  includes  our  entire  mental  organization. 

In  the  course  of  this  study  several  general  problems  have 
no  doubt  occurred  to  the  reader  which  are  of  more  than 
theoretical  interest.  Every  one  of  us  asks  himself  at  one 
time  or  another  to  what  extent  his  personality  is  fixed  by 
heredity,  and  how  far  it  is  molded  by  his  special  environment. 
We  often  wonder  at  the  great  differences  that  appear  between 
different  individuals.  The  most  practical  question  of  all  is 
how  far  we  can  mold  our  own  lives  and  control  our  environ- 
ment. These  three  great  problems  of  personality  may  be 
stated  as  follows: 

What  are  the  factors  in  menial  organization? 
What  different  types  of  mind  are  found  in  man? 
To  what  extent  do  we  personally  control  our  environment 
and  the  course  of  oiu:  own  lives? 

Mental  Organization.  —  The  term  organization  is  applied 
to  any  complicated  structure  whose  several  parts  perform 
different  operations  but  all  work  together  to  accomplish  some 
definite  result.  A  locomotive  is  an  organization;  its  various 
parts  do  different  things,  but  all  parts  cooperate  to  make  the 
machine  go  and  to  regulate  its  movements.  Living  crea- 
tures are  organizations  '  whose  organs  perform  different  vital 
processes,  but  all  work  together  to  maintain  the  life  of  the 
creature  and  perpetuate  the  species.  The  social  organiza- 
tion of  man  has  the  same  general  characteristics;  a  govern- 
ment or  an  industrial  concern  includes  many  human  beings 
who  perform  different  duties,  but  they  all  cooperate  to  accom- 
pUsh  certain  general  results. 

Our  mind,  or  mental  organization,  is  the  joint  product  of 
'  This  particular  kind  of  organization  is  called  an  organism. 


366  PERSONALITY  AND  CONTROL      [ch.  xvi 

two  distinct  sets  of  factors:  (1)  An  inherited  physical  stnie- 
ture  consisting  of  the  nervous  system  with  its  receptors  and 
effectors.  (2)  Acquired  experiences  and  modifications  of  this 
structure  due  to  stimuH  and  other  forces  which  act  upon  it. 
Examining  more  closely,  we  can  break  these  up  into  six  sepa- 
rate factors: 

Inherited  structure 
Terminal  organs  and  conducting  nerves 
Central  nervous  system 

Effects  of  external  and  internal  forces 
Disorganizing  influences 
Stimuli  and  general  siurounding  conditions 
Social  influences 
Educational  influences 

a.  Terminal  Organs  and  Conducting  Nerves:  The 
receptors  and  effectors  are  the  two  terminals  of  the  nervous 
system.  These  terminal  organs,  joined  together  by  chains  of 
connecting  neurons  and  intermediate  centers,  are  responsible 
for  the  great  diversity  in  our  experiences. 

The  wealth  of  different  sensations  which  we  get  in  sight 
and  hearing  is  due  to  the  complexity  of  the  eye  and  ear.  No 
matter  how  many  kinds  of  stimuli  existed  in  the  environment 
they  would  all  give  us  the  same  kind  of  sensation  if  the  recep- 
tors were  not  constructed  in  such  a  way  as  to  receive  them 
differently.  The  number  of  different  sensations  we  are  cap- 
able of  having  depends  on  the  degree  of  development  of  our 
sense  organs.  Color  blindness  shows  how  the  number  of 
color  sensations  is  lessened  when  the  eye  is  imperfectly 
developed. 

In  the  same  way  the  variety  of  different  motor  responses 
that  we  are  capable  of  making  depends  on  the  multiplicity 
of  muscles  and  glands.  A  game  knee  or  a  stiff  finger-joint 
will  interfere  with  a  surprisingly  large  number  of  coordinated 
movements.  Notice  how  a  glove  on  the  hand  hampers  many 
simple  manual  tasks.    Notice  what  a  number  of  muscles  all 


CH.  XVI  ]  MENTAL  ORGANIZATION  367 

over  the  body  are  concerned  in  the  movements  of  rising  to 
your  feet  and  in  keeping  your  equilibrium.  Clear  pronun- 
ciation and  the  varied  intonations  of  the  human  voice  require 
the  cooperation  of  numerous  muscles  of  the  jaw,  tongue,  lips, 
cheeks,  throat,  and  thorax. 

The  motor  organs  are  more  substitutive  than  the  receptors. 
If  certain  muscles  are  wanting  we  can  often  develop  some 
other  combination  that  will  serve  the  same  purpose.  A  man 
bom  without  arms  may  be  trained  to  use  his  feet  for  hands 
and  his  toes  for  fingers.  But  this  motor  substitution  has 
definite  limits.  No  group  of  human  muscles  has  succeeded  in 
accomplishing  aerial  flight.  Nothing  in  the  lower  animals 
quite  takes  the  place  of  the  human  thumb. 

The  conducting  nerves  may  be  regarded  as  part  of  the 
receiving  and  reacting  machinery.  The  sensory  nerves  con- 
vey the  impulses  from  receptors  to  centers.  If  there  is  a 
break  anywhere  in  the  chain,  the  information  is  not  received. 
In  the  same  way  the  motor  nerves  convey  motor  impulses 
from  the  centers  to  the  effectors.  They  are  part  of  the 
*  motor  mechanism.'  In  short,  the  inherited  terminal  organs 
and  conducting  nerves  determine  the  number  of  different 
sensations  that  a  man  can  have,  and  the  number  of  different 
responses  that  he  can  make. 

6.  Central  Nervous  System:  The  central  nervous  sys- 
tem is  the  most  important  part  of  our  mental  endowment. 
It  is  the  means  by  which  we  put  together  the  mosaic  of  infor- 
mation and  use  it  effectively  in  our  actions.  Even  though 
our  receptors  are  defective,  or  if  some  are  entirely  lacking,  we 
can  often  get  equivalent  information  from  other  senses,  so 
that  we  can  meet  the  ordinary  situations  of  life  effectively. 
The  blind  and  the  deaf  can  think  and  reason  as  well  as  the 
normal  person  if  their  central  system  is  unimpaired. 

The  same  is  true  on  the  motor  side.  It  goes  without  say- 
ing that  there  can  be  no  movement  without  muscles;  but  th« 
coordination  and  fine  adjustment  of  muscular  movements  is 


368 


PERSONALITY  AND  CONTROL      [ch.  xvi 


JMrTiK 


brought  about  by  the  central  nervous  system.  A  study  of 
handwriting  will  demonstrate  this.  First  write  a  phrase  in 
the  ordinary  way;  then  write  it  in  very  small  letters,  using 
only  finger-movements;  finally  write  the  same  phrase  in 
large  letters  on  the  blackboard,  keeping  your  wrist  and  fingers 
rigid  and  using  only  the  elbow  and  shoulder.  In  the  two 
last  cases  entirely  different  muscles  are  used;  yet  there  is  a 
marked  similarity  between  all  three  results.    [Fig.  80.]   This 

shows  that  the  individu- 
ality of  a  man's  handwrit- 
ing is  due  to  characteris- 
tics of  the  nerve  impulses 
from  his  brain  centers, 
not  to  the  constitution  of 
his  muscles.  The  reedu- 
cation of  crippled  soldiers 
demonstrates  the  same 
thing  in  another  way. 
The  brain,  and  in  a  lesser 
way  the  lower  reflex  cen- 
ters, are  the  organs  of  ad- 
justment. This  central 
system  enables  us  to 
'  grasp  '  the  environment 
and  respond  suitably  to 
the  situations  presented 
to  us.  Man's  mental  su- 
premacy is  due  almost 
wholly  to  his  inheritance 


Fig.  80.  — Handwriting  with  Diffeb- 

ENT  Muscles 

The  upper  writing  was  made  with  wrist  and  fin- 
gers. (Slightly  reduced  in  the  cut.)  In  the  middle 
specimen  only  the  fingers  were  used.  The  speci- 
men below  was  made  with  sweeping  movements  of 
elbow  and  shoulder  on  a  large  blackboard;  wrist 
and  fingers  rigid.  (Much  reduced  in  the  cut.) 
Although  entirely  different  muscles  were  used  in 
the  second  and  third,  the  writings  are  similar, 
showing  that  individuality  in  handwriting  is  due  to 
the  coordinated  motor  impulse  sent  from  the  writ- 
ing  center  in  the  brain.  ^j   ^   j^j^j^j^  COmplcX   CCyf- 

teXy  furnished  with  a  vast  number  of  interconnecting  neurons. 
Integration  of  stimuli,  coordination  of  responses,  and  adjust- 
ment of  response  to  stimulation  all  depend  upon  the  central 
nervous  system  and  especially  upon  the  cortical  tracts. 
These  are  all  inherited  structures. 


CH.  xvi]  MENTAL  ORGANIZATION  S69 

c.  Disorganizing  Influences:  The  inherited  structure 
which  governs  mental  processes  is  Hable  to  be  impaired  in 
various  ways  by  the  destructive  action  of  agencies  that  lie 
outside  our  body.  Our  eyesight  may  be  injured  by  over- 
exposure to  light  or  by  some  sharp  body  mutilating  the 
eyeball.  The  loss  of  a  foot  or  hand  cripples  our  motor  ex- 
pression. Injury  to  the  brain  by  a  fall  or  other  acci- 
dent often  leads  to  serious  disturbance  of  the  adjustive  func- 
tions. 

There  are  also  disorganizing  influences  within  the  body 
itself.  A  tumor  in  the  braiti  affects  the  structure  of  certain 
centers  or  their  operation,  and  this  may  give  rise  to  patho- 
logical mental  manifestations,  such  as  aphasia.  Malnutri- 
tion, disorders  of  digestion  or  other  vital  functions,  persistent 
use  of  narcotics,  stimulants,  and  other  drugs,  may  alter 
the  course  of  mental  activity  to  such  an  extent  as  to  affect 
a  man's  character  and  personality  profoundly.  Thomas 
Cariyle's  pessimistic  attitude  is  attributed  to  his  chronic 
dyspepsia.  Diseases  which  destroy  the  tissues  may  affect 
the  nerve  substance  or  some  of  the  receptors  or  effectors. 
Deafness  may  be  brought  on  by  measles;  infantile  paralysis 
impairs  the  power  of  locomotion. 

All  such  effects  represent  the  destructive  action  of  the 
environment  on  our  inherited  mental  organization,  since  even 
the  destructive  agencies  within  the  body  may  generally  be 
traced  to  something  harmful  in  the  environment. 

We  can  look  at  the  matter  this  way :  Nature,  through  our 
heredity,  has  furnished  us  with  a  splendid  apparatus  for  using 
our  environment  to  promote  our  life  interests.  This  appara- 
tus is  admirably  fitted  to  cope  with  all  ordinary  situations. 
But  it  does  not  provide  against  every  contingency.  It  is 
liable  to  injury  and  destruction.  Yet  we  can  often  cope  suc- 
cessfully with  these  disorganizing  factors  in  an  indirect  way. 
We  can  avoid  destructive  weapons,  shun  infection,  keep  our 
body  in  good  condition  by  regular  living.    Even  when  unf ore- 


370  PERSONALITY  AND  CONTROL      [ce.  xvi 

seen  or  unavoidable  circumstances  injure  the  apparatus,  our 
mental  and  social  organization  often  provides  a  means  of 
repairing  the  injmy.  Medicine,  surgery,  therapeutics,  and 
education  may  cure  the  disorder  or  train  some  other  organ  to 
take  the  place  of  the  one  that  is  impaired. 

d.  Stimuli  and  General  Surrounding  Conditions: 
Mental  organization  becomes  effective  by  use.  "What  we 
inherit  is  merely  the  capacity  for  certain  reflexes  and  instinc- 
tive actions  and  the  possibility  of  acquiring  intelligent 
responses.  These  possibilities  become  actual  modes  of 
behavior  only  when  stimulation  occurs.  Even  the  simplest 
reflex  path  has  to  be  joined  up  before  it  can  be  used.  Unless 
the  proper  stimuli  occur  at  a  certain  period  of  life  the  connec- 
tion may  never  be  made,  as  we  find  in  the  case  of  the  ear- 
twitching  reflex. 

Intelligent  actions  are  even  more  dependent  on  stimulation. 
Their  nerve  paths  are  not  ready  for  use  at  the  start.  The 
connections  are  established  slowly,  by  repetition  of  the  same 
stimuli.  We  do  not  inherit  language,  or  thought,  or  such 
special  activities  as  house  building  and  automobile  steering, 
in  the  same  way  that  we  inherit  walking  and  eye-movement. 
Our  inherited  nerve  structure  merely  makes  intelligent  action 
possible.  The  ability  to  perform  the  act  is  acquired  and 
perfected  gradually  through  the  working  of  stimuli  upon  the 
nervous  system. 

There  is  one  striking  difference  between  the  nervous  mech- 
anism and  man-made  machines.  A  machine  may  limber  up 
and  do  better  work  after  the  first  few  trials,  but  after  that  it 
does  not  improve,  —  and  it  does  not  develop  totally  new  uses. 
One  can  scarcely  imagine  a  harvesting-machine  being  con- 
verted into  a  printing-press.  Our  nervous  organization,  on 
the  contrary,  improves  continually  by  use,  and  admits  of 
most  astonishing  adaptations.  The  human  hand,  with  the 
nervous  system  to  guide  it,  is  used  for  tilling  the  soil,  for 
feeding,  and  for  writing. 


CH.  xvi]  MENTAL  ORGANIZATION  871 

In  addition  to  particular  stimuli,  mental  life  depends  upon 
certain  general  and  relatively  permanent  conditions  of  the 
environment.  Climate  and  temperature,  abundance  or 
scarcity  of  food,  the  presence  of  material  for  protection  and 
defense,  assist  in  determining  what  our  life  shall  be. 

In  short,  the  course  of  our  mental  life  and  the  progress  of 
its  organization  depend  not  merely  upon  our  inheriting  a 
certain  nervous  structure,  but  upon  our  using  that  structure. 
The  direction  of  mental  development  is  determined  by  the 
action  of  forces  outside  and  inside  the  body,  working  upon 
the  inherited  nervous  system. 

e.  Social  Influences  :  Social  situations  are  perceived  by 
the  very  same  senses  that  inform  us  of  things  in  general. 
There  is  no  distinct  *  social  sense.'  But  social  forces  differ 
in  many  important  ways  from  other  external  forces,  and  the 
situations  which  they  represent  play  a  peculiar  part  in  mental 
organization.  Because  our  fellow  men  have  a  nervous  sys- 
tem similar  to  our  own,  and  because  their  aims  and  interests 
in  life  are  of  a  piece  with  ours,  social  stimuli  have  a  different 
effect  from  other  stimuli. 

Language  and  the  whole  process  of  communication  depend 
upon  the  presence  of  a  social  environment.  The  develop- 
ment of  thought  is  assisted  by  the  fact  that  one  man's  mental 
processes  are  much  like  another's.  Our  ability  to  speak 
readily  and  think  clearly  is  apt  to  be  impaired  by  constant 
seclusion  from  the  world,  though  alternation  of  solitary  and 
social  conditions  often  stimulates  rational  thinking. 

The  extent  to  which  the  development  of  mental  life 
depends  on  social  influences  is  shown  by  certain  instances  of 
children  brought  up  apart  from  human  surroundings.  In 
the  case  of  Kasper  Hauser,  whose  early  years  were  apparently 
devoid  of  social  intercourse,  intellectual  development  was 
irremediably  stunted.  He  could  never  be  raised  above  the 
condition  of  an  imbecile.'  Helen  Keller,  cut  off  from  social 
*  This  may  have  been  due  to  hereditary  deficiencies. 


872  PERSONALITY  AND  CONTROL      [ch.  xvi 

stimuli  through  blindness  and  deafness,  made  no  progress  in 
mental  growth  till  taken  in  hand  by  an  expert  teacher. 

Much  of  our  mental  growth  in  childhood  is  due  to  sub- 
conscious absorption  of  ideas  and  imitation  of  customs  from 
those  about  us.  Our  mental  organization  is  molded  after 
the  pattern  of  the  community  in  which  we  live.  An  indi- 
vidual with  a  certain  heredity  may  become  a  notorious  crimi- 
nal or  a  power  for  good,  according  as  he  is  placed  in  an  unfa- 
vorable or  favorable  social  environment.  The  example  set 
by  others  excites  a  molding  influence  on  mental  development, 
even  apart  from  education. 

/.  Educational  Influences:  Education  in  the  sense  of 
organized  teaching  is  a  separate  factor  in  mental  life.  It  is 
the  systematic  effort  of  society  to  develop  the  mental  organiza- 
tion of  its  members. 

Teaching  occurs  in  a  rudimentary  form  in  primitive  races, 
but  its  real  significance  is  seen  in  the  higher  stages  of  civiliza- 
tion, where  it  exerts  a  tremendous  influence  in  developing 
the  mind.  Beginning  with  home  and  church  training  it 
extends  through  the  schools  to  the  university  and  to  technical 
institutions  of  every  sort.  By  means  of  systematic  training 
mental  growth  is  *  forced  '  —  mental  organization  develops 
at  a  rate  far  exceeding  that  attained  through  the  mere  influ- 
ence of  social  example. 

Human  personaHty  and  mental  organization  depend  upon 
every  one  of  these  six  factors.  They  are  all  needed  in  a 
systematic  explanation  of  what  we  are  and  why  we  think  and 
act  as  we  do.  The  student  of  human  nature  realizes  how 
dependent  a  man  is  upon  his  parentage  and  surroundings, 
and  is  more  inclined  to  sympathize  with  the  dullard,  the 
social  misfit,  and  the  criminal  than  to  condemn  them.  This 
sympathy  should  not  take  the  form  of  mawkish  sentiment, 
but  should  aim  to  remedy  their  disabilities  as  far  as  possible. 

Education,  not  punishment,  is  the  means  to  use.     If  the 


CH.  xvi]  MENTAL  ORGANIZATION  878 

defect  is  without  remedy  we  can  at  least  find  an  environment 
suited  to  the  individual's  limitations.  The  '  lunatic  asylum  ' 
has  given  place  to  the  *  hospital  for  the  insane.'  There  are 
training  schools  for  the  mentally  defective,  and  special 
classes  for  dull  students.  The  prison  system  should  empha- 
size the  educational  side  —  especially  moral  education  — 
instead  of  the  penal  side.  Applied  psychology  has  an  im- 
portant task  before  it  in  picking  out  suitable  occupations  for 
social  misfits.  A  feeble-minded  boy  who  had  set  fire  to 
several  houses  was  committed  to  the  Vineland  institution. 
They  assigned  him  the  duty  of  tending  the  furnace.  From 
a  dangerous  criminal  he  was  transformed  into  a  useful  work- 
man. 

Mental  Tjrpes.  — When  we  compare  human  beings  we  find 
striking  differences  in  both  the  degree  and  the  type  of  their 
mental  development.  The  variations  in  degree  of  develop- 
ment or  mental  level  are  measured  by  mental  tests  (ch.  xv). 
Varieties  in  menial  type  are  qualitative  difiPerences  between 
the  minds  of  various  men.  Each  type  of  mind  represents 
a  predominance  of  some  phase  of  mental  life.  The  most 
significant  differences  are  found  in  sensory  types  and  types  of 
character. 

The  differences  of  sensory  type  have  been  examined  ex- 
perimentally. One  person  is  found  to  be  preeminently  a 
visualist.  He  is  eye-minded.  In  his  case  the  visual  sensa- 
tions and  images  are  especially  vivid  and  form  the  most 
prominent  part  of  his  mental  experiences.  He  must  see  a 
thing  before  he  can  understand  it.  He  learns  by  reading 
better  than  by  listening.  In  science  his  interest  is  in  the 
microscope  or  in  maps.  If  he  is  an  author,  his  books  abound 
in  color  terms  and  visual  pictures. 

Another  person  is  of  the  auditory  type.  He  is  ear-minded. 
He  thinks  in  terms  of  the  sound  of  words.  He  understands 
oral  instructions  readily,  so  that  he  learns  more  easily  from 
listening  to  lectures  than  from  poring  over  text-books;  he  ia 


374  PERSONALITY  AND  CONTROL      [ch.  xvi 

quick  at  *  mental '  arithmetic.  His  auditory  imagery  and  in 
most  cases  his  appreciation  of  music  are  developed  above  the 
average. 

A  third  belongs  to  the  motor  type.  He  is  muscle-minded. 
With  him  language  is  primarily  a  motor  phenomenon;  he 
thinks  in  terms  of  sensations  from  the  vocal  muscles,  and  his 
imagery  is  largely  of  muscular  movements.  He  is  quick  at 
memorizing  speeches;  his  interest  is  in  motor  activity.  A 
deaf-blind  person  is  probably  of  the  tactile  type. 

It  is  a  mistake  to  assume  that  every  one  belongs  distinc- 
tively to  one  of  these  types.  In  some  cases  the  mental 
organization  is  rather  evenly  balanced.  In  many  persons 
certain  activities  are  preeminently  of  the  visual  type  while 
other  activities  are  based  upon  motor  or  auditory  data.  A 
man  may  be  an  '  auditory  linguist '  in  one  tongue  and  a 
*  visual  linguist '  in  another.  He  may  be  a  visualist  in 
geometry  and  of  the  motor  type  in  physics.  The  growth  of 
types  depends  partly  on  inherited  brain  structure  and  partly 
on  circumstances  of  training.  In  the  earlier  stages  of  educa- 
tion it  is  important  to  train  the  type  of  imagery  and  thought 
along  the  lines  best  suited  to  each  particular  topic.  Later, 
when  we  find  out  the  type  to  which  the  child  naturally  be- 
longs, it  is  wiser  to  fit  the  educational  method  so  far  as 
possible  to  the  individual :  teach  the  visuaHst  through  books, 
the  audile  person  by  oral  instruction. 

The  growth  of  character  brings  out  another  set  of  types. 
In  certain  persons  the  intellectual  side  is  dominant,  in  others 
temperament,  in  others  skill.  When  we  speak  of  a  tempera- 
mental personality,  we  mean  that  the  person  referred  to  is 
subject  to  frequent  sweeping  changes  of  temperament;  this 
is  usually  accompanied  by  deep  emotional  displays.  An 
intellectual  man  looks  at  the  world  from  an  unemotional, 
logical  point  of  view;  and  so  on. 

There  are  individuals  in  whom  the  various  phases  of 
character  are  mingled,  but  with  a  decided  bent  of  mind  in 


CH.  xvi]  MENTAL  TYPES  375 

some  definite  direction.  You  have  no  difficulty  in  distin- 
guishing a  timid  mind,  a  nasty  mind,  a  schemer,  an  aggres- 
sive personality,  a  snobbish  nature.  Some  persons  develop 
traits  of  manner,  voice,  and  thought  such  that  they  are 
known  to  every  one  as  having  an  *  attractive '  personality; 
others  seem  to  be  inherently  '  iminteresting.'  Various  other 
types  might  be  added  to  the  list:  the  *  slobbery  '  man,  the 
*  bellyacher,'  the  dreamer. 

The  development  of  these  types  depends  largely  on  in- 
herited nervous  structure;  certain  brain  centers  may  be  more 
highly  developed,  or  some  of  the  connective  nerve  tracts. 
But  use  and  systematic  training  can  foster  certain  phases  of 
character  and  check  the  growth  of  others.  John  Stuart  Mill 
seems  to  have  been  by  nature  of  the  esthetic  type.  Under 
his  father's  rigid  intellectual  schooling  he  grew  into  a  pro- 
nounced intellectualist.  His  case  is  somewhat  exceptional 
in  that  the  drastic  training  was  successful.  Usually  the 
attempt  to  divert  a  person's  mental  life  into  entirely  new 
channels  is  disastrous.  In  the  interests  of  the  man's  happi- 
ness it  is  wiser  to  mold  his  character,  from  childhood  onward, 
along  the  lines  of  his  natural  propensities,  taking  care  only 
to  eliminate  any  overdevelopment  of  one  side  which  might 
hamper  his  social  or  moral  welfare. 

Control.  —  A  question  of  great  practical  importance  in  life 
is  how  and  to  what  extent  a  person  can  control  his  own 
actions  and  cope  with  the  situations  with  which  he  is  con- 
fronted. The  subject  has  unfortunately  been  coupled  in 
the  popular  mind  with  speculative  theories  concerning 
human  *  freedom  '  to  think  and  act.  Om*  study  of  mental 
processes  has  shown  that  men  do  not  think  and  act  in  an 
arbitrary  manner.  The  succession  of  thoughts  depends 
on  definite  principles  of  association  and  proceeds  in  an  or- 
derly way  —  new  thoughts  are  not  spontaneously  generated. 
Psychology  assumes  that  voluntary  decisions  are  definitely 
determined  by  principles  of  mental  activity,  and  not  by 


876  PERSONALITY  AND  CONTROL      [ch.  xvi 

chance.  We  never  pull  ourselves  completely  away  from  our 
own  character  and  personality  by  sheer  will,  any  more  than 
we  can  pull  ourselves  off  the  earth  by  tugging  at  our  own 
boots. 

The  psychological  problem  of  control  has  no  relation  to 
these  philosophical  gymnastics.  It  is  concerned  with  the 
eflSciency  of  man's  mental  organization.  There  are  two 
questions  involved:  (1)  What  are  the  processes  by  means  of 
which  a  human  being  controls,  directs,  guides  his  own  life? 
(2)  What  does  this  control  accomplish? 

(1)  Means  of  Control:  Every  response  is  an  exercise  of 
control.  Reflex  actions  show  this  control  in  its  most  rudi- 
mentary form.  The  reflex  wink  protects  the  eye;  swallowing 
carries  food  to  the  digestive  organs.  Many  reflexes  which 
taken  by  themselves  have  no  special  significance,  are  essen- 
tial parts  of  organized  actions.  The  autonomic  processes  of 
digestion,  circulation,  etc.,  are  splendid  instances  of  control 
and  regulation,  but  they  are  mainly  concerned  with  the 
maintenance  of  the  body  substance  and  not  with  our  re- 
sponses to  external  situations. 

The  three  most  important  means  of  control  are  instinctive 
actions,  intelligent  actions,  and  the  special  type  of  intelli- 
gence called  rational  actions. 

Instinctive  behavior  is  especially  effective  in  controlling  the 
permanent,  stable  features  of  the  environment.  The  bee's 
honey-gathering  actions  are  useful  because  there  are  honey- 
giving  flowers  in  every  bee's  environment  at  certain  seasons 
of  the  year.  The  nest-building  instinct  of  birds  is  effective 
because  there  are  trees  and  materials  for  constructing  nests 
in  the  bird's  environment.  The  preying  activities  of  some 
animals  and  the  grazing  activities  of  others  are  due  to  certain 
permanent  features  of  the  world  in  which  these  animals  live. 

Intelligent  behavior  is  effective  in  controlling  more  change- 
able situations.  Voluntary  actions  usually  deal  with  situa- 
tions that  are  at  least  partly  new.     When  you  catch  a  ball, 


CH.  xvi]  MEANS  OF  CONTROL  377 

your  movements  depend  on  the  speed  and  angle  of  the  ball, 
both  of  which  factors  are  open  to  all  sorts  of  variation. 
Speaking  and  writing  bring  about  useful  results  because  we 
utter  or  write  different  words  according  to  circumstances. 
Inventions  and  social  customs  spring  up  from  time  to  time 
and  change  continually;  we  learn  to  operate  machines  and  to 
follow  social  customs  by  intelligent  responses. 

Rational  behavior  is  based  on  the  fact  that  nature  is  uni- 
form —  that  physical,  chemical,  biological,  and  mental 
events  take  place  according  to  permanent,  enduring  princi- 
ples; but  it  depends  quite  as  much  on  the  fact  that  the 
situation  varies  from  time  to  time.  The  airplane  inventor 
and  the  pilot  who  runs  the  plane  must  take  into  considera- 
tion both  the  general  principles  of  aeronautics  and  the 
varying  conditions  which  a  plane  will  encounter. 

(2)  Objects  of  Control:  What  is  it  that  we  control? 
The  simplest  sort  of  control  is  control  of  our  own  responses. 
In  the  case  of  reflex  and  instinctive  behavior  this  control  is 
practically  complete.  Inherited  nerve  paths  enable  the 
creature  to  make  the  proper  movements  from  the  start.  In 
the  case  of  intelligent  and  rational  actions  we  learn  to  control 
our  movements  by  slow  degrees.  At  first  the  motor  outcome 
is  generally  wrong.  Step  by  step  we  acquire  control  of  our 
muscles  and  do  what  we  have  planned  to  do.  The  process  is 
one  of  central  adjustment.  We  learn  to  improve  our  motor 
coordinations  by  means  of  our  higher  brain  centers.  There 
is  apparently  no  limit  to  the  improvement. 

Another  variety,  slightly  different  from  this,  is  control  of 
ourselves.  Self-control  is  confined  almost  wholly  to  man  and 
is  due  to  the  development  of  higher  brain  centers.  Man 
learns  to  inhibit  or  modify  his  own  systemic  and  motor 
processes.  This  is  illustrated  in  the  repression  of  emotion 
and  less  obviously  in  the  regulation  of  our  daily  work.  The 
special  significance  of  this  kind  of  control  lies  in  the  fact  that 
it  enables  us  to  govern  the  course  of  our  own  life.     This 


378  PERSONALITY  AND  CONTROL      [ch.  xvi 

means  a  distinct  advance  in  efficiency.  To  master  the 
tongue  —  and  the  fist  —  is  a  mark  of  high  mental  develop- 
ment. The  man  who  can  control  himself  can  usually  con- 
trol others. 

A  more  significant  type  of  control,  so  far  as  outward  results 
are  concerned,  is  the  ability  to  modify  the  environment  itself 
by  our  actions  in  such  a  way  as  to  assist  our  life  processes. 
When  primitive  man  prepared  skins  of  animals  and  used 
them  to  clothe  and  protect  himself,  he  advanced  a  step  to- 
ward control  of  his  environment.  The  making  of  forest  trails, 
building  of  huts,  sowing  of  fields,  and  domestication  of 
animals  are  other  early  instances  of  man's  active  influence 
upon  the  physical  world.  Ships,  railroads,  harvesters, 
lighting  plants,  and  all  the  products  of  modern  industry  may 
be  regarded  as  instruments  for  the  control  of  nature  by  man. 

Along  the  same  line  is  the  improvement  of  our  receptors 
and  effectors  by  artificial  devices.  Man  has  succeeded  in 
overcoming  to  a  large  extent  the  natural  limitations  of  his 
senses  and  motor  organs.  He  has  devised  spectacles,  the 
microscope,  and  the  telescope  to  supplement  his  eyes.  The 
telephone  extends  the  range  of  the  human  ear.  Weighing 
scales  take  the  place  of  hefting  with  our  hands;  the  ther- 
mometer adds  precision  to  our  temperature  senses.  Our 
motor  organs  are  supplemented  in  the  same  way.  The 
hammer  takes  the  place  of  the  human  fist;  the  bicycle  and 
railroad  train  increase  man's  locomotor  ability;  the  plow, 
crane,  and  countless  other  tools  supplement  his  arms  and 
hands.  These  measuring  instruments  and  tools  may  be 
treated  as  artificial  receptors  and  effectors,  developed  by 
human  intellect  and  skill  instead  of  through  biological 
evolution.  They  are  added  means  for  controlling  our  en- 
vironment. 

Still  another  type  is  social  control.  By  means  of  language 
a  human  being  is  able  to  guide  the  actions  of  his  fellows  and 
is  guided  in  turn  by  them.     Your  control  of  other  men  may 


CH.  xvi]  OBJECTS  OF  CONTROL  379 

be  regarded  as  part  of  your  control  of  your  environment. 
But  when  you  yourself  are  governed  by  social  influences  a 
new  phase  of  control  arises.  Your  own  mind  is  no  longer  the 
supreme  director  of  your  behavior.  The  center  of  control  is 
shifted  to  some  other  mind  or  to  the  collective  influence  of 
the  community.  The  soldier  and  the  hired  servant  are  con- 
trolled by  other  human  minds.  The  office  holder  in  a  demo- 
cratic nation  is  subject  to  control  by  the  group.  The  actions 
of  individuals  in  any  community  are  determined  largely  by 
custom  and  tradition;  to  this  extent  we  are  all  subject  to 
group  control. 

The  growth  of  our  mental  organization  may  be  either  pro- 
moted or  impeded  by  social  control.  The  training  of  chil- 
dren and  systematic  education  of  every  sort  illustrate  the 
useful  side.  One  is  often  inspired  to  better  things  by  the 
example  of  others.  Psychotherapy  is  the  improvement  of 
bodily  and  mental  conditions  by  suggestion.  The  discipline 
of  the  workshop  and  the  army  are  useful  on  the  economic 
side,  though  they  tend  to  diminish  a  man's  independence  and 
self-reliance. 

Social  control  is  distinctly  bad  when  one  individual  comes 
so  fully  under  the  domination  of  another  that  his  mental 
growth  is  seriously  thwarted.  The  slave  and  the  profes- 
sional hypnotic  subject  illustrate  the  harmful  working  of 
social  control.  The  result  here  is  mental  deterioration 
instead  of  mental  development. 

Control  is  the  most  significant  feature  of  behavior.  Our 
motor  activities  are  effective  just  so  far  as  they  serve  to 
control  our  environment  or  our  bodily  organization.  Civi- 
lized man,  through  the  enormous  development  of  his  brain, 
by  means  of  his  acquired  information  and  motor  habits,  and 
with  the  aid  of  measuring  instruments  and  tools  of  his  own 
devising,  is  able  to  guide  his  own  destiny.  He  learns  to 
govern  himself  and  others.  He  directs  his  motor  acts  and  is 
able  to  alter  his  environment  to  a  large  extent  —  to  change 


880  PERSONALITY  AND  CONTROL      [ch.  xvi 

the  face  of  nature.  He  is  at  once  "  master  of  his  fate  "  and 
"  captain  of  his  soul." 

Conclusion:  Practical  Bearings  of  Psychology.  —  In  this 
book  we  have  been  attempting  to  study  in  a  systematic  way 
the  characteristics  of  human  nature.  Man  is  a  being  who 
experiences  and  acts.  His  experiences,  we  have  found,  are 
built  up  out  of  sensations  obtained  through  the  receptors  and 
nervous  system,  which  inform  him  concerning  his  environ- 
ment. These  separate  sensations  are  organized  into  percep- 
tions, memories,  emotions,  thoughts,  volitions,  language,  and 
other  definite  sorts  of  experience.  The  repetition  of  similar 
experiences  builds  up  special  and  general  attitudes,  and  these 
mold  the  different  sides  of  his  character.  The  final  summa- 
tion of  our  entire  experience  life  is  personality. 

On  the  active  side,  mental  life  starts  with  isolated  responses 
to  isolated  stimuli.  These  separate  reflexes  are  organized 
into  instinctive  acts,  and  by  the  learning  process  they  develop 
into  intelligent  acts,  of  which  rational  action  is  a  specialized 
form.  By  means  of  these  various  forms  of  behavior  we  come 
more  and  more  to  control  our  movements,  our  bodily  organs, 
our  fellow  men,  and  the  world  about  us.  The  final  outcome 
of  this  progressive  organization  of  behavior  is  our  personal 
control  of  the  whole  situation. 

There  is  a  special  glamour  surrounding  the  mysterious. 
The  conjurer  who  extracts  eggs  from  your  mouth  and 
rabbits  from  your  pocket  attracts  your  interest.  The  spell 
is  gone  when  you  discover  how  the  trick  is  performed.  The 
mysterious  workings  of  the  human  mind  arouse  our  wonder 
in  much  the  same  way.  Will  this  feeling  be  dispelled  alto- 
gether when  we  discover  the  orderly  way  in  which  mental  life 
proceeds?  Let  us  hope  not.  The  study  of  psychology  gives 
us  a  clue  to  the  workings  of  the  most  wonderful  contrivance 
in  existence  —  a  mechanism  which  has  enabled  man  to  col- 
lect a  tremendous  mass  of  information  about  the  world  in 
which  he  lives,  to  use  this  information  for  furthering  his  aims 


CH.  xvi]    APPLICATIONS  OF  PSYCHOLOGY  381 

in  life,  and  to  transform  the  face  of  nature  itself.  Should  we 
not  feel  greater  admiration  and  awe  when  we  realize  that 
all  this  is  accomplished  by  means  of  the  same  orderly  processes 
that  operate  throughout  nature? 

Our  present  study  has  necessarily  been  limited  to  funda- 
mental facts  and  principles.  When  these  are  mastered,  we 
are  in  a  position  to  branch  out  into  more  practical  fields.  If 
we  understand  how  the  grown-up  human  mind  works,  we 
can  compare  its  processes  with  those  of  the  child  mind  and 
with  the  mental  processes  of  animals. 

A  knowledge  of  psychological  principles  will  assist  us  in 
our  own  mental  training  —  in  our  efforts  to  form  new  habits 
or  break  bad  ones,  to  govern  our  passions,  to  become  socially 
fit,  to  judge  men,  to  understand  their  faihngs. 

Psychology  has  many  practical  applications.  One  of  its 
fields  is  to  assist  in  selecting  the  most  suitable  man  for  any 
given  position  —  industrial,  scholastic,  or  political.  If  we 
know  our  own  type  of  mind  it  will  help  us  in  choosing  our 
career.  The  judge  and  the  physician  must  appreciate  the 
significance  of  mental  deficiency  in  order  to  treat  their  *  cases  ' 
correctly.  The  lawyer  and  the  preacher  must  understand 
the  workings  of  the  human  mind  in  order  to  make  their 
pleas  effective.  In  these  and  other  directions  a  knowledge 
of  scientific  psychology  is  of  the  utmost  value. 

Every  one  has  some  inkling  of  how  the  mind  works,  just 
as  every  one  has  a  smattering  of  chemical  and  physical  facts. 
But  amateur  knowledge  is  a  long  way  behind  accurate 
knowledge.  Which  of  us  would  undertake,  without  training, 
to  run  a  locomotive?  Yet  the  human  mind  is  far  more 
complex  than  any  man-made  contrivance.  It  is  true  that 
the  mind  is  to  a  large  extent  self-acting.  We  are  capable 
of  meeting  situations  by  our  own  native  power  of  mental 
adjustment.  But  if  we  wish  to  use  our  mind  effectively,  and 
if  we  would  cope  successfully  with  the  minds  of  others,  our 
untutored  insight  and  judgment  are  not  suflScient.    We  must 


CONCLUSION  [CH.  XVI 

understand  the  fundamental  principles  of  mental  life  as 
formulated  by  psychology. 

Practical  Exercises: 

81.  Analyze  how  far  your  personality  appears  to  be  due  to  heredity  and 
how  far  to  your  social  environment. 

82.  Determine  so  far  as  possible  to  what  sensory  type  or  types  you  belong. 

83.  Describe  instances  you  have  observed  of  the  growth  of  control  in 
various  directions  —  emotional  expression,  sketching,  systematic  study, 
moral  conduct;  if  possible  take  your  own  case  as  one  instance. 

84.  What  is  your  present  idea  of  mind  ? 

85.  Give  instances  from  your  own  observation  of  notably  good  and  bad 
effects  arising  from  social  control  of  one  person  by  another. 

References: 

On  the  self -notion:  J.  M.  Baldwin,  Social  and  Ethical  Interpretations,  ch.  1. 
On  multiple  personality:  M.  Prince,  Dissociation  of  a  Personality. 
On  applications  of  psychology:  H.  Miinsterberg,  Psychology,  General  and 
Applied,  bk.  iii. 


REVIEW  QUESTIONS  883 

REVIEW  QUESTIONS 

Chaptbb  I 

What  is  meant  by  mental  life?   What  is  the  distinction  between  mental 

and  biological  life? 
In  what  way  does  interplay  occur  between  the  creature  and  his  environment? 
What  kinds  of  questions  do  we  consider  in  human  psychology? 
What  is  meant  by  (1)  self-study,  (2)  behavior  study,  and  (3)  nerve  study? 
Distinguish  between  observation  and  experiment.     How  may  observation 

and  experiment  be  used  in  behavior  study? 
Describe  the  various  branches  of  psychology. 
What  branches  of  psychology  might  undertake  a  study  of  play?     (Give 

reasons  why  each  should  be  included.) 
Dehne  human  psychology,  and  describe  the  method  of  study  used  in  this 

book. 

Chapter  n 

Mention  six  different  kinds  of  cells  in  the  human  body. 

How  does  a  neuron  differ  from  a  muscle  cell? 

Describe  the  axon. 

How  are  neiu-ons  connected  together? 

Name  the  parts  of  the  cerebrospinal  system. 

Distinguish  between  sensory  and  motor  jjeripheral  nerves. 

Distinguish  between  spinal  and  cranial  nerves. 

How  do  sensory  nerves  enter  the  cord?    How  do  motor  nerves  go  out  of  the 

cord?    Where  do  sensory  and  motor  nerves  join? 
What  is  the  gray  matter  in  the  spinal  cord?     How  do  you  account  for  the 

H  shape  of  the  gray  matter? 
How  does  a  nerve  impulse  pass  from  the  left  side  of  the  body  to  the  right 

side  of  the  brain? 
Describe  the  medulla  oblongata;  the  cerebellimi;  the  pons  Varolii;  the  basal 

ganglia;  the  cortex. 
Where  are  the  centers  for  moving  various  parts  of  the  body  located  in  the 

cortex? 
Describe  the  position  of  the  several  lobes  of  the  brain  in  relation  to  one 

another  and  to  the  fissures. 
Distinguish  between  projection  centers  and  association  areas. 
Describe  the  autonomic  system.     How  is  the  autonomic  system  related  to 

the  cerebrospinal  system? 

Chapter  HI 

Describe  a  simple  nervous  arc. 

What  are  the  five  successive  steps  in  every  case  of  nervous  activity? 


384  REVIEW  QUESTIONS 

Describe  the  course  of  the  nerve  impulse  in  the  nervous  arc  when  an  insect 

Ughts  upon  your  hand  and  you  turn  your  eyes  to  look  at  it. 
How  is  a  nerve  impulse  started,  and  what  determines  its  intensity  and 

quality?     (Illustrate  in  the  case  of  a  sound.) 
What  is  meant  by  excitation? 

What  is  the  peculiarity  of  conduction  along  a  nerve  fiber? 
Point  out  the  difference  between  retention  and  fatigue  in  the  nervous  system, 

giving  an  example  of  each. 
What  are  the  properties  of  collection  and  distribution? 
Why  are  our  actions  called  responses? 
Distinguish  between  muscular  and  glandular  responses,  and  describe  just 

what  occurs  in  each. 
What  is  meant  by  (1)  integration,  (2)  coordination,  and  (3)  adjustment? 
Describe  the  adjustment  process  at  any  moment  in  the  case  of  some  one 

reading  music  and  playing  it  on  the  piano  or  violin. 

Chapter  IV 

Give  a  classification  of  the  senses. 

Describe  the  structure  of  the  eye. 

Describe  the  various  motor  functions  concerned  in  sight. 

Describe  the  process  of  focusing  light  on  the  retina.     How  do  near-sight  and 

far-sight  affect  this  process? 
Explain  the  relations  between  changes  in  hue,  shade,  and  tint. 
How  are  color  relations  shown  on  the  color  spindle? 
What  are  the  primal  colors  and  how  do  we  determine  this  fact? 
WTiat  is  meant  by  complementary  colors? 
Distinguish  between  positive  and  negative  after-sensations. 
What  is  color  blindness?     Describe  its  most  common  form  and  how  it  may 

be  tested. 
How  does  the  Ladd-Franklin  theory  of  sight  reconcile  the  three  fundamental 

colors  with  the  four  primal  colors? 


Chapter  V 

Describe  the  arrangement  of  the  middle  ear  and  cochlea. 

What  differences  in  the  stimuli  for  hearing  produce  (1)  deep  tones,  (2)  shrill 

tones,  (3)  loud  tones,  (4)  faint  tones,  (5)  noises? 
Distinguish  between  absolute  pitch  and  relative  pitch. 
How  are  overtones  produced?    What  is  timbre? 
Explain  how  beats  and  difference  tones  are  produced. 
Describe  the  receptor  and  stimuli  for  smell. 
Describe  the  relation  of  the  various  sorts  of  odors. 
Describe  the  receptor  and  stimuli  for  taste. 
How  do  you  account  for  differences  in  the  flavor  of  foods,  if  there  are  only 

four  qualities  of  taste? 


REVIEW  QUESTIONS  385 

Describe  the  receptors  for  cutaneous  sensations.    Name  some  of  the  qualh> 

ties  of  touch  sensation. 
What  evidence  have  we  that  touch,  warmth,  cold,  and  pain  are  distinct 

senses? 
Mention  some  of  the  principal  organic  sensations  and  discuss  the  sensation  ot 

hunger. 
What  is  the  stimulus  for  pain,  and  what  is  the  pain  receptor? 
What  information  is  furnished  by  the  muscle  sense? 
Describe  the  receptor  for  the  static  sense. 
What  evidence  have  we  that  the  semicircular  canals  are  receptors  for  static 

sensations? 
Distinguish  between  the  external,  systemic,  and  motor  senses. 
Discuss  the  relative  importance  of  the  different  senses. 

Chapter  VI 

If  consciousness  is  not  a  concrete  thing,  how  can  it  be  studied? 

What  is  meant  by  impression  and  suggestion? 

Show  the  relation  between  retention  and  revivaL 

What  is  meant  by  attention? 

What  is  meant  by  fusion  and  colligation? 

What  is  meant  by  discrimination? 

Distinguish  between  a  sensation  and  an  erperience. 

What  kinds  of  experiences  are  composed  of  a  single  class  of  sensations? 

What  three  faults  are  found  in  the  writings  of  psychoanalysts? 

Give  an  example  of  subliminal  consciousness. 

Describe  an  experience  occurring  in  the  subordinate  6eld  of  consciousness. 

Describe  conditions  of  anesthesia  and  hyperesthesia. 

Chaptek  VII 

What  is  the  relation  of  perception  to  sensation? 

Why  do  perceptions  sometimes  fail  to  indicate  the  real  relations  of  external 
objects? 

Why  is  the  difference  between  64  lbs.  and  62  lbs.  less  noticeable  than  the 
difference  between  4  lbs.  and  2  lbs.? 

Explain  Weber's  Law. 

What  factors  are  involved  in  the  perception  of  surfaces? 

Describe  the  chief  factors  in  the  visual  perception  of  depth  with  one  eye. 

How  does  the  difference  between  the  two  eyes  assist  in  our  perception  of 
depth? 

Why  does  the  stereoscope  give  the  illusion  of  depth? 

What  is  meant  by  projection? 

How  does  the  space  perception  of  the  blind  differ  from  that  of  normal  per- 
sons? 

Describe  Stratton's  experiment  on  reversing  the  field  of  vision.  What  light 
does  it  throw  on  space  perception? 


386  REVIEW  QUESTIONS 

Explain  how  we  perceive  motion  and  actions. 

Why  do  we  overlook  misprints  and  misread  printed  words? 

How  do  you  account  for  the  Bering  (or  the  Miiller-Lyer)  illusion? 

What  activities  of  the  central  nervous  system  are  involved  in  perception? 

What  sort  of  training  is  useful  to  improve  perception? 

Chapter  VIII 

Why  do  we  seldom  have  images  of  systemic  and  motor  sensations? 
Distinguish  between  memory  and  imagination. 
What  nervous  conditions  and  processes  are  essential  to  memory? 
What  is  meant  by  projection  of  memory  images,  and  what  does  this  projec- 
tion accomplish? 
What  is  meant  by  the  feeling  of  familiarity? 
Explain  the  laws  of  association,  with  examples  of  each. 
How  does  the  rate  of  forgetting  change  with  the  length  of  time  elapsed? 
Give  three  reasons  why  you  forget. 

Why  does  the  strength  of  memory  depend  on  the  training  of  perception? 
Why  do  children  confuse  their  fancies  with  their  recollections? 
Distinguish  between  fancies  and  anticipation  images. 
How  do  general  images  differ  from  memory  images? 
How  do  we  distinguish  mental  images  from  perceptions? 

Chapter  IX 

Distinguish  between  intellectual  and  affective  experiences. 

How  is  the  special  quality  of  a  systemic  sensation  related  to  its  feeling  tone? 

Under  what  conditions  can  we  experience  two  conflicting  feelings  at  once? 

If  feelings  are  experiences  in  which  the  systemic  sensations  are  the  main 
elements,  how  do  oiu*  perceptions  of  external  things  come  to  have  a  feeling 
tone? 

Distinguish  between  appetite  and  aversion. 

How  does  the  intensity  of  feeling  vary  with  increased  mtensity  of  stimula- 
tion? 

Distinguish  between  feeling  and  emotion. 

Explain  the  James-Lange  theory  of  emotion,  and  mention  some  of  the  evi- 
dence for  and  against  it. 

How  far  can  observations  of  emotions  in  animals  be  used  in  the  study  of 
human  emotions? 

Describe  the  most  primitive  emotions. 

Discuss  the  classification  of  emotions  given  in  this  chapter.  Why  is  it  diflS* 
cult  to  classify  emotions? 

To  what  extent  are  the  emotions  unsuited  to  civilized  conditions? 

Are  beauty  and  power  in  the  objects  or  in  the  mind? 

Describe  the  sentiments  of  belief,  disbelief,  and  doubt. 

Why  are  sentiments  generally  unimportant  in  mental  life? 


REVIEW  QUESTIONS  387 

Chaptek  X 

What  is  the  relation  between  a  motor  experience  and  a  response? 
Demonstrate  the  fact  that  every  stimulus  tends  in  the  end  to  bring  about 

some  response. 
Distinguish  between  diffused  movements  and  reflexes. 
In  what  respects  do  the  autonomic  functions  belong  to  psychology? 
Distinguish  between  lower  and  higher  reflexes,  giving  an  example  of  each. 
Describe  the  various  relations  that  may  occur  between  different  muscles 

concerned  in  compound  reflexes. 
Explain  the  scientific  notion  of  instinct,  and  compare  it  with  the  popular 

notion. 
How  do  instincts  originate  in  any  species,  according  to  the  theory  of  natural 

selection? 
Discuss  the  classification  of  instincts  given  in  this  chapter. 
Why  has  man  very  few  pure  instincts  and  many  modified  instincts? 
Distinguish  between  the  clothing  instinct  and  the  modesty  instinct. 
Discuss  imitation. 

To  what  extent  are  instincts  present  at  birth? 
To  what  extent  does  your  present  behavior  rest  on  an  instinctive  basis? 

Chapter  XI 

Distinguish  between  the  effects  of  fatigue  and  adaptation. 

Describe  the  way  in  which  a  conditioned  reflex  is  acquired. 

Describe  the  transition  from  instinctive  to  intelligent  behavior. 

How  is  acquisition  related  to  fixation? 

Explain  the  nervous  processes  involved  in  acquisition. 

Discuss  the  effect  of  repetition,  intensity,  recency,  and  conflict  on  the  fixa- 
tion process,  with  examples  of  each. 

How  may  the  laws  of  speed  and  accuracy  in  habit-formation  be  demon- 
strated experimentally? 

Criticize  the  theory  that  habits  are  lapses  of  intelligence. 

Describe  an  instance  of  trial-and-error  learning,  (a)  in  the  case  of  an  animal; 
(6)  in  man. 

Describe  the  method  of  learning  through  associative  memory. 

Show  by  two  examples  how  complex  habits  are  made  up  of  simpler  habits. 

How  may  habits  detrimental  to  our  welfare  be  broken? 

Chapter  XII 

In  what  important  respect  do  motor  experiences  differ  from  other  sorts  of 

experiences? 
Describe  the  sensations  found  in  conations. 

Describe  reflex  conations,  instinctive  conations,  and  habit  conations. 
Distinguish  between  sensorimotor  and  ideomotor  actions. 
Distinguish  between  conations  and  volitions. 
Discuss  the  theory  that  all  ideomotor  actions  are  the  result  of  learning. 


S88  REVIEW  QUESTIONS 

Explain  what  is  meant  by  deliberation  and  choice. 

What  is  the  significance  of  a  delayed  response? 

Explain  the  statement  that  when  we  vxill  to  do  a  certain  thing,  we  have  a 

thought  of  the  action,  together  with  certain  muscle  sensations  of  effort 

or  memories  of  such  sensations. 
In  what  respect  does  a  purpose  differ  from  other  thoughts? 
Show  how  volition  assists  us  to  control  ourselves  and  our  environment. 
Discuss  the  natiu«  of  ideals. 

Chapter  XIII 

Show  how  a  word  may  tend  to  replace  an  image. 

What  are  the  special  characteristics  of  language  and  thought? 

Why  are  language  and  thought  called  symbolic  experiences? 

Explain  why  language  is  especially  adapted  for  communication. 

Why  is  speech  superior  to  gesture  as  a  means  of  communication? 

Why  is  mirror-script  difficult  to  read  and  write? 

Point  out  how  the  social  environment  is  a  factor  in  the  acts  of  reading  and 

speaking. 
Discuss  the  special  brain  centers  for  language  and  thought. 
Describe  the  prominent  disorders  of  language. 
Show  the  relation  of  meaning  to  rational  thought. 
Distinguish  between  meaning  and  value,  with  examples  of  each. 
What  is  the  relation  of  judgment  to  thought? 
Why  is  rational  behavior  superior  to  trial  and  error  behavior? 
Contrast  the  evolution  of  emotion  and  thought. 

What  is  the  educational  significance  of  the  training  of  thought  and  language? 
Discuss  the  various  levels  of  the  nervous  arc  and  their  relation  to  experience 

and  behavior. 

Chapter  XIV 

In  what  ways  are  our  present  experiences  influenced  by  our  past? 

To  what  extent  is  the  simile  of  the  stream  of  consciousness  correct? 

How  is  the  speed  of  perception  measured? 

Describe  the  method  of  determining  the  reaction  time  of  an  association. 

What  factors  determine  the  flow  of  perceptions? 

What  are  the  principal  factors  that  determine  the  flow  of  thought? 

What  secondary  influences  determine  the  flow  of  thought? 

In  what  ways  is  the  flow  of  thought  subject  to  personal  control? 

Describe  the  chief  characteristics  of  dreams  and  dreaming. 

Why  are  dreams  incongruous  and  absurd? 

Describe  the  characteristics  of  hypnotic  experiences. 

How  does  reasoning  differ  from  ordinary  thinking? 

Why  do  our  inferences  tend  to  agree  with  real  events  and  general  truths? 

Why  do  we  commit  logical  fallacies? 

Why  are  our  inferences  sometimes  wrong  when  we  reason  correctly? 


REVIEW  QUESTIONS  389 

Explain  what  is  meant  by  rationalization. 

Describe  how  the  various  sorts  of  experiences  enter  into  the  general  stream 
of  mental  life. 

Chapter  XV 

What  is  meant  by  a  permanent  mental  condition? 

How  are  mental  attitudes  built  up? 

Discuss  the  relation  between  interest,  desire,  and  attention. 

What  classes  of  experiences  arouse  interest? 

Distinguish  between  want  and  satisfaction. 

How  are  emotional  dispositions  related  to  emotion? 

Describe  the  problem  attitude. 

How  far  does  a  moral  attitude  depend  on  mental  development,  and  how  far 
on  social  tradition? 

Point  out  the  relation  of  character  to  attitudes  and  to  experiences. 

How  are  the  phases  of  hmnan  character  related  to  the  several  classes  of  sen- 
sations? 

Distinguish  between  height  and  breadth  of  intellect. 

Describe  the  principle  of  the  Binet-Simon  tests. 

How  is  temp)erament  related  to  feeling  and  activity? 

Why  is  it  desirable  to  have  ratings  of  skill? 

Distinguish  between  motives  and  the  actual  results  of  moral  conduct. 

Discuss  the  psychological  theory  of  reward  and  punishment. 

Chapter  XVI 

Why  is  it  diflScult  to  measure  personality? 

Describe  the  experience  of  personal  identity. 

What  are  the  characteristics  of  multiple  personality? 

Trace  the  growth  of  the  notion  of  self. 

What  is  included  in  mental  organization? 

Why  is  the  central  nervous  system  more  important  in  mental  life  than  the 
receptors  and  muscles? 

Mention  some  of  the  disorganizing  influences  that  hinder  mental  growth. 

To  what  extent  are  stimuli  helpful  in  building  up  mental  organization? 

Distinguish  between  social  and  eduoational  influences  on  mental  growth. 

Distinguish  between  the  visual  and  auditory  types  of  mind. 

What  is  meant  by  a  temperamental  personality? 

How  does  intelligent  behavior  assist  us  in  exercising  control? 

Distinguish  between  control  of  our  own  responses  and  control  of  the  environ- 
ment. 

Point  out  the  benefits  and  dangers  of  social  control. 

How  does  psychology  help  the  lawyer  and  the  judge?  the  physician?  the 
employer?    the  educator? 


SUGGESTIONS  IN  USING  THE  BOOK 

This  text  is  intended  for  use  in  a  full-year  introductory 
course;  it  may  be  used  in  a  half-year  course  with  certain 
omissions. 

The  chapters  generally  cover  about  the  same  amount  of 
material,  the  longer  ones  being  somewhat  easier,  and  the 
shorter  ones  more  difficult.  For  a  briefer  course  the  sections 
on  the  structure  of  the  eye  and  ear  (chs.  iv,  v)  may  be 
omitted.  To  equalize  assignments  the  latter  part  of  chapter 
vii  (illusions,  etc.)  might  be  postponed  and  taken  up  in  con- 
nection with  chapter  xii;  it  would  not  be  advisable  to  omit 
or  curtail  the  discussion  of  the  structure  and  operation  of 
the  nervous  system  (chs.  ii,  iii). 

The  References  at  the  end  of  the  chapters  are  limited  to 
special  topics  of  general  interest,  about  which  the  student 
might  wish  to  seek  further  information  on  his  own  initiative. 
They  should  not  be  assigned  for  required  reading. 

The  Practical  Exercises  are  intended  to  train  the 
student  in  first-hand  observation  of  mental  phenomena. 
The  author  has  found  them  to  be  the  most  useful  part  of  his 
own  courses.  One  exercise  is  required  of  the  student  every 
week.  The  class  is  given  an  option  between  two  or  three 
exercises;  one  of  the  alternative  exercises  is  within  the  ex- 
perience of  every  student  (e.g.,  Exercises  1,  2),  another  may 
deal  with  some  special  topic  and  be  available  to  certain 
students  only  (e.g..  Exercises  4,  21). 

The  exercises  should  be  handed  in  regularly  and  promptly. 
Their  usefulness  is  greatly  diminished  if  they  are  performed 
weeks  after  the  topic  has  been  under  discussion.  Aside  from 
a  deduction  of  credit  for  tardiness  or  obvious  carelessness,  it 
is  not  advisable  to  grade  the  exercises.    If  an  exercise  is  pep- 


392  SUGGESTIONS 

formed  seriously  and  handed  in  on  time,  it  should  be  ac- 
cepted and  given  full  credit,  however  amateurish  the  result. 

The  length  of  the  report  need  not  be  prescribed.  Often  a 
brief  report  of  two  hundred  words  is  more  satisfactory  than  a 
long  essay.  The  point  to  insist  upon  constantly  is  that  the 
student  shall  make  each  observation  for  himself,  and  not 
rely  on  his  general  information  or  on  popular  tradition,  or 
repeat  the  descriptions  contained  in  the  book.  The  form  of 
the  report  should  embody  this  idea.  It  should  be  in  the 
first  person:  "  I  saw  so-and-so  ";  "The  movements  in  my 
face  and  head  were — ."  The  instructor  should  discounte- 
nance such  expressions  as,  "  When  one  says  the  word  man 
aloud,  he — ."  The  short-story  style,  with  its  artistic  em- 
bellishments, is  tempting  to  most  students,  but  it  is  rarely  as 
satisfactory  as  a  plain  description.  If  the  exercises  are 
handed  back  within  a  week,  with  a  few  suggestive  comments, 
it  will  be  found  that  after  two  or  three  attempts  most  stu- 
dents get  the  right  idea. 

It  is  well  to  caution  the  class  at  the  outset  against  the 
following  sources  of  error  in  the  exercises:  (1)  Careless  read- 
ing of  the  problem,  so  that  its  real  meaning  is  not  understood. 

(2)  Careless  observation  —  especially  of  familiar  experiences. 

(3)  Attempting  to  explain  the  experiences,  instead  of  report- 
ing them;  or  mingling  an  account  of  what  (probably)  occurs 
in  the  nervous  system  with  the  account  of  what  the  individual 
himself  actually  observes.  (4)  Casual  observation  in  place  of 
measurements  where  the  exercise  is  in  the  nature  of  an  experi- 
ment or  test.  (5)  Describing  the  action  of  children  or  others 
in  terms  of  the  observer's  own  personal  experience,  instead  of 
observing  and  reporting  their  actual  behavior.  (6)  Substi- 
tuting traditional  and  popular  notions  of  mental  phenomena 
for  the  student's  own  personal  observation. 

The  Review  Questions  following  chapter  xvi  are  in- 
tended to  assist  the  student  in  mastering  the  contents  of  the 
text.     They  prevent  casual  reading,  by  challenging  the  stu- 


SUGGESTIONS  393 

dent  to  explain  the  meaning  of  what  he  has  read.  The 
student  who  has  read  the  assignment  but  cannot  answer  the 
questions  is  still  unprepared.  The  set  of  questions  given 
here  do  not  include  classifications  or  definitions.  It  is  doubt- 
ful on  psychological  grounds  whether  a  student  should 
memorize  a  mere  list  of  terms,  such  as  the  table  of  Emotions. 
This  feat  of  memory  will  not  advance  his  knowledge  of 
psychology  materially.  Definitions  are  distinctly  useful, 
though  a  word-for-word  reproduction  ought  not  to  be  in- 
sisted on.  This  type  of  question  is  omitted  here  because 
abundant  material  can  be  readily  drawn  from  the  glossary 
at  the  end  of  the  book,  or  from  the  text  itself. 

An  excellent  way  of  treating  definitions  in  a  written  exami- 
nation is  by  the  completion  method :  Print  the  definition  word 
for  word  in  the  examination  paper,  omitting  certain  signifi- 
cant terms  with  a  blank  in  their  place.  The  student  has 
merely  to  fill  in  each  blank  with  the  proper  word  —  a  great 
saving  of  time. 

The  Glossary  includes  definitions  of  the  principal  terms 
used  in  this  book.  The  wording  is  in  many  cases  more  precise 
than  that  of  the  text;  it  aims  to  bring  out  the  distinction  be- 
tween cognate  words.  Carrying  out  this  idea,  the  popular 
use  of  certain  terms  is  contrasted  with  their  special  meaning 
adopted  in  this  book.  A  few  useful  technical  terms  not  found 
in  the  text  are  included. 

It  is  suggested  that  the  student  consult  the  glossary  for 
terms  which  come  up  constantly  in  class  discussions,  if  the 
meaning  is  not  entirely  clear.  The  page  references  include 
only  the  principal  treatment  of  a  term.  Where  the  reference 
covers  several  pages,  the  number  is  followed  by  *f '  or  (where  a 
large  section  is  involved)  'ff';  *n'  after  a  number  refers  to  a 
footnote.  Those  interested  in  the  finer  meanings  of  terms  are 
advised  to  consult  Baldwin's  Dictionary  of  Philosophy  and 
Psychology. 

The  principles  of  psychology  have  many  practical  and  per- 


394  SUGGESTIONS 

sonal  Applications.  Both  in  examinations  and  in  the  oral 
quizzes  the  instructor  will  find  it  useful  to  ask  questions 
which  bring  home  to  the  student  the  intimate  relation  of 
psychology  to  every-day  life:  "  Describe  the  emotions  you 
experience  at  a  ball  game  ";  "  How  does  the  nerve  impulse 
travel  in  your  body  when  you  hear  a  sound  and  turn  your 
head  toward  it?  " 

Interest  in  the  course  will  be  greatly  increased  if  frequent 
Class-room  Demonstrations  are  introduced.  Models  of 
the  eye  and  ear  are  almost  essential  to  an  understanding  of 
the  structure  of  these  complex  organs.  A  human  brain  or  a 
model  (as  in  Fig.  1)  should  be  exhibited  if  possible;  also 
microscope  slides  showing  sections  of  the  brain  and  spinal 
cord,  and  of  different  types  of  neurons. 

A  simple  experiment  in  habit  formation  or  memorizing  can 
readily  be  made  in  class.  The  chain  reaction  (Exercise  71) 
can  be  performed  in  groups  of  ten  to  twenty  persons  even 
without  a  stop-watch.  Association  experiments  can  be 
made  with  two  or  three  volunteers  and  their  results  com- 
pared. Many  other  demonstrations,  such  as  optical  illusions, 
stereoscopic  vision,  color-mixing,  overtones,  etc.,  can  be 
arranged  without  an  elaborate  outfit. 

Where  funds  are  available  for  special  Apparatus,  and  the 
schedule  allows  time  for  experimental  work  in  connection 
with  the  course,  one  of  the  standard  laboratory  manuals 
should  be  consulted.  For  experiments  requiring  practically 
no  apparatus,  see  Seashore's  Elementary  Experiments  in 
Psychology.  Excellent  experiments  with  a  few  special 
apparatus  are  found  in  Langfeld  and  Allport's  Elementary 
Laboratory  Course  in  Psychology.  A  great  variety  of  experi- 
ments and  demonstrations  are  collected  in  Sanford's  Course 
in  Experimental  Psychology.  The  most  complete  laboratory 
manual  in  English  is  Titchener's  Experimental  Psychology 
(4  Volumes). 


GLOSSARY  AND  INDEX 


[For  attggestions  as  to  use,  see  page  S9S\ 


Aboulia  =  a  phase  of  mental  disorder 
characterized  by  inability  to  make 
decisions,  280 

Accommodation,  neural  =  the  for- 
mation of  new  synaptic  connec- 
tions, opening  up  a  new  path  in 
the  nervous  system,  255 

—  visual  =  change  in  shape  of  the 
lens  as  we  focus  for  a  different  dis- 
tance, 59,  65 

Accommodation  muscle  (or  Ciliary 
muscle)  =  a  muscle  which  regu- 
lates the  curvature  of  the  eye-lens, 
59,63 

—  sensations  =  sensations  stimulat- 
ed by  tension  of  the  accommoda- 
tion muscle,  153  f 

Accuracy,  see  Elimination 

Acquisition  =  the  formation  of  a 
new  nervous  arc,  resulting  in  a  new 
response  to  a  given  stimulus,  253  f 

—  relation  to  fixation,  253,  261 
Action  =  in    psychology:  movement 

of  a  living  creature,  produced  by 
motor  nerve  impulses  affecting  the 
muscles,  2  f 

—  stream  of  =  the  succession  of  re- 
sponses which  constitute  the  motor 
or  expressive  life  of  an  individual, 
328 

Active  (or  Activity)  experience  =  an 
experience  derived  mainly  from 
the  motor  senses,  120;  cf.  Cona- 
tion 

Adaptation  (or  Adaptive  response) 
=  any  response,  whether  inherited 
or  acquired,  which  is  appropriate 
to  the  situation  presented  by  the 
stimuli;  i.e.  which  promotes  the 
creature's  life  processes,  228,  247 

—  instinctive  =  the  evolution  of  in- 
stincts in  the  animal  series,  resiilt- 
ing  in  more  suitable  forms  of  re- 
sponse, 236 


—  intelligent  =  improvement  of  be- 
havior due  to  acquisition  of  a  bet- 
ter neural  adjustment  by  the  in- 
dividual, 250,  262 

—  visual  =  the  changes  which  occur 
in  the  visual  receptors  when  we 
pass  from  bright  to  dim  illumina- 
tion or  vice  versa,  76 

Adjustment  =  the  systematic  collec- 
tion and  distribution  of  nerve  im- 
pulses in  the  brain,  whereby  the 
response  becomes  adapted  (appro- 
priate) to  the  stimulus ;  a  combina- 
tion of  integration  and  coordina- 
tion, 52  f 

Affective  (or  Hedonic)  =  pertaining 
to  the  systemic  senses  or  to  feeling, 
120 

—  experience  =  an  experience  de- 
rived mainly  from  the  systemic 
senses,  120,  203;  cf.  Feeling 

Afferent  (or  Centripetal)  =  sensory, 
leading  from  a  receptor  toward  the 
center 

After-sensation  (or  Afterimage)  = 
a  sensation  which  continues  or  ap- 
pears after  the  stimulus  has  ceased, 
77 

—  negative  =  an  after-sensation 
which  is  the  complement  of  the 
original  sensation,  77 

—  positive  =  an  after-sensation  sim- 
ilar to  the  original  sensation,  77 

Ageusia  =  loss  of  the  sense  of  taste 

Agraphia  =  a  phase  of  mental  dis- 
order characterized  by  inability 
to  express  thought  in  writing,  294 

Alexia  =  a  phase  of  mental  disorder 
characterized  by  inability  to  read, 
294 

Algesthesia,  see  Pain  sense 

Alpha  tests  =  a  scale  for  measuring 
intellectual  ability,  used  in  the 
United  States  Army,  348 


S96 


GLOSSARY  AND  INDEX 


Ampulla  =  an  enlargement  at  the 
base  of  the  semicircular  canals,  118 

Anabolism  =  chemical  changes 
which  build  up  the  bodily  tissues, 
112 

Analgesia  =  loss  of  the  pain  sense 

Anesthesia  =  (a)  a  condition  of  the  re- 
ceptors or  sensory  nerves  in  which 
stimuli  fail  to  arouse  sensation,  139 ; 
(b)  loss  of  the  sense  of  touch 

—  in  hypnosis,  321 
Anger  emotion,  213 

Anosmia  =  loss  of  the  sense  of  smell 
Antagonists  (or  Antagonistic  mus- 
cles) =  a  pair  of  muscles  which 
move  the  same  member  in  oppo- 
site directions,  51,  232 
Aphasia,  motor  =  a  phase  of  mental 
disorder  characterized  by  inability 
to  speak,  293 

—  sensory  =  a  phase  of  mental  dis- 
order characterized  by  inability  to 
understand  spoken  words,  293  n 

Apopathetic  instincts  =  instinctive 
behavior  determined  by  the  pres- 
ence of  others  in  the  individual's 
environment,  240 

Appetite  =  feeling  characterized  by 
pleasantness,  206 

Appreciation  =  (a)  an  attitude  em- 
bodying the  permanent  effects  of 
thought  and  memory,  340  f;  (b) 
commonly:  the  evaluative  atti- 
tude, 341 

Arborization  =  the  ramification  of 
fibrils  at  the  end  of  a  neuron,  21 

Arc,  see  Nervous  arc 

Aristotle's  experiment,  of  the  crossed 
fingers,  164 

Association  =  the  succession  of  one 
thought  or  image  after  another,  or 
of  an  idea  after  a  perception,  313 

—  laws  =  a  formulation  of  the  man- 
ner in  which  successive  ideas  arise, 
185,  313 

—  verbal  =  (a)  the  association  of  a 
name  (verbal  symbol)  with  some- 
thing perceived  or  imagined,  182, 
192,  289;  (b)  association  of  one 
word  with  another  through  mere 
similarity  in  sound,  324 

Association  area  =  a  region  of  the 


cortex  composed  of  nerve  tissue 
connecting  projection  centers  in 
the  same  hemisphere,  33 

Association  time  =  the  duration  of 
that  portion  of  a  nervous  process 
which  is  concerned  in  association 
of  one  idea  with  another,  311 

Associative  memory,  see  Learning 

Astigmatism  =  a  condition  of  the 
eye-lens  in  which  the  vertical  and 
horizontal  curvatures  differ,  65  n 

Attention  =  (a)  the  mental  process 
of  focusing  certain  parts  of  an  ex- 
perience so  that  they  become  more 
vivid,  128,  333  n;  (b)  an  attitude 
embodying  the  permanent  effects 
of  motor  experiences,  335  f 

—  span  =  the  number  of  objects  dis- 
tinctly perceived  at  a  single  mo- 
ment, 163 

Attitude  =  the  manner  in  which  an 
individual  receives  experiences,  so 
far  as  this  is  determined  by  the 
deep,  lasting  traces  left  in  the  ner- 
vous structure  by  frequent  repeti- 
tion of  experiences  of  the  same 
fundamental  type,  331,  332  3 

—  emotional,  see  Disposition 

—  ideal,  344 

—  sentimental  =  an  attitude  which 
embodies  the  permanent  effects  of 
sentimental  experiences,  e.g.  cre- 
dulity, arising  from  belief,  338 

—  social,  see  Conscience 

—  classification,  334 

—  evolution,  343 

—  subconscious  factors,  344 
Audition,  see  Hearing 
Aufgabe,  see  Problem  attitude 
Automatic  response,  see  Response 
Autonomic  function  =  a  coordinated 

chain  or  group  of  reflexes  in  the 
autonomic  nervous  system,  which 
actuate  the  bodily  processes  of  di- 
gestion, circulation,  etc.,  226 

—  system,  see  Nervous  system 
Aversion  =  feeling  characterized  by 

unpleasantness,  206 
Awareness,  see  Consciousness 
Axon  (or  Axone)  =  the  long  project- 
ing fiber  of  the  neuron  or  nerve 
cell,  21 


GLOSSARY  AND  INDEX 


397 


Basal  ganglia  {or  Basal  masses)  = 
masses  of  nerve  tissue  in  the  cere- 
brum beneath  the  cortex;  they  in- 
clude the  optic  thalami,  corpora 
striata,  corpora  quadrigemina, 
crura  cerebri,  etc.,  30 

Beat  =  a  quaver  effect  which  arises 
when  two  nearly  similar  tones  are 
sounded  together,  96;  cf.  Dif- 
ference tone 

Beauty  sentiment,  219 

Behavior  =  action  or  activity  of  any 
sort  which  results  from  the  opera- 
tion of  the  nervous  arc  in  an  or- 
ganism, 225  ff 

—  instinctive  =  a  coordinated  chain 
or  group  of  diverse  reflexes  which 
work  together  systematically,  ow- 
ing to  inherited  neural  conditions, 

227,  233  ff 

—  intelligent  =  a  coordinated  set  of 
responses  whose  cooperation  is  due 
in  part  to  alteration  and  improve- 
ment of  the  inherited  neural  con- 
nections by  individual  acquisition, 

228,  250  ff 

—  rational  =  the  motor  result  of  ra- 
tional thought;  a  specialized  type 
of  intelligent  behavior,  298 

—  reflex,  see  Reflex 

—  classification,  225 

—  levels,  302  f 

Behavior  study  =  the  study  of  the 
manner  in  which  organisms  re- 
spond to  stimulation,  8 

Belief  =  the  sentiment  or  conviction 
that  certain  ideas  represent  real 
facts  or  relations,  220, 222 

Binet-Simon  scale  =  a  graded  series 
of  mental  tests  for  measuring 
intellectual  growth  in  children, 
347 

Binocular  {or  Stereoscopic)  vision 
=  perception  with  the  two  eyes, 
presenting  a  single  visual  field  in 
which  objects  stand  out  in  relief, 
156  f 

Black  =  a  visual  sensation  which 
arises  without  the  usual  light-wave 
stimulation,  69,  82 

Blind  spot  =  a  break  in  the  retina  to 
the  nasal  side  of  the  fovea,  where 


the  optic  nerve  enters  the  eyeball, 
60 
Brain  =  that   part   of   the   nervous 
system  which  lies  within  the  head, 
i.e.  above  the  spinal  cord,  3,  29  f 

—  relation  to  consciousness,  124 
Brain-stem  =  all   the   brain   except 

the  cerebellum  and  cortex"  with 
connecting  tracts,  29  n 

Brightness  {or  Value)  =  intensity  of 
visual  sensations,  Tl;  cf.  Shade 

Broca  convolution  {or  area)  =  the 
posterior  (dorsal)  part  of  the  in- 
ferior frontal  convolution;  the 
word-speaking  center 

Callosum  {or  Corpus  callosum)  =  a 
mass  of  nerve  tissue  beneath  the 
cortex,  which  connects  the  right 
and  left  hemispheres,  31,  33 

Canals,  semicircular  =  an  organ  in 
the  inner  ear  which  serves  as  re- 
ceptor for  the  static  sense,  87,  117 

Catabolism  =  destructive  chemical 
changes  in  the  bodily  tissues,  112 

Cell  =  an  organized  mass  of  proto- 
plasm in  the  living  body;  the  unit 
of  organic  structure,  19  f 

Cell-body  =  the  compact  body  of  a 
neuron,  exclusive  of  the  branches, 
21 

Censor  =  a  term  of  doubtful  pro- 
priety applied  to  the  organized 
subconscious  life,  134 

Centers  =  regions  in  the  nervous 
system  where  sensory  impulses 
pass  over  into  motor  impulses,  31, 
122 

—  cortical  {or  control,  projection)  = 
regions  in  the  cortex  where  im- 
pulses from  or  to  the  primary  cen- 
ters are  collected  or  distributed,  32, 
33 

—  language  {or  speech)  and  thought 
=  special  regions  in  the  cortex 
(usually  confined  to  the  left  hemi- 
sphere), where  thought  and  lan- 
guage activities  occur  and  where 
motor  impulses  for  communicative 
expression  originate;  they  form  the 
adjustment  center  of  the  highest 
nervous  arc,  32,  34,  292  f 


898 


GLOSSARY  AND  INDEX 


—  primary  =  the  terminal  of  sensory 
or  motor  paths  in  the  lower  part 
of  the  brain,  31,  33 

—  spinal  =  a  connecting-point  be- 
tween sensory  and  motor  nerves 
in  the  spinal  cord,  37 

Cerebellum  =  a  large  mass  of  nerve 
tissue  back  of  the  medulla  and 
above  it,  forming  part  of  the  brain, 
30 

Cerebrospinal  system,  see  Nervous 
system 

Cerebrum  =  the  upper  part  of  the 
brain,  including  all  portions  above 
the  medulla  and  cerebellum;  di- 
vided into  two  hemispheres,  30  f; 
(accent  on  first  syllable) 

Character  =  (a)  the  organized  effect 
of  all  attitudes  derived  from  the 
same  fundamental  type  of  expe- 
rience, 331,  345  ff;  (b)  any  charac- 
teristic 

—  phase  of  =  any  one  of  the  four 
great  divisions  of  personality,  346; 
cf.  Intellect,  Temperament,  Skill, 
Morality 

—  training,  356 

Chiasm,  optic  =  the  point  of  junc- 
ture of  right  and  left  optic  nerves, 
34,  65 

Choice,  voluntary  =  discharge  of  the 
motor  impulse  into  the  least  re- 
sistant path  in  voluntary  action, 
277 

Choroid  coat  =  the  intermediate 
coating  of  the  eyeball,  between  the 
sclerotic  and  retina,  60  n 

Chroma,  see  Saturation 

Chronoscope,  Hipp  =  a  clockwork 
with  dials  and  hands  for  measuring 
short  intervals  of  time,  11,  308  f 

Clang,  compound  =  the  total  audi- 
tory effect  of  two  or  more  tones 
sounded  together,  96 

—  simple  =  the  auditory  effect  of  a 
tone  with  its  overtones,  95;  cf. 
Overtone 

Cochlea  =  a  spiral  structure  in  the 
inner  ear  containing  the  receptors 
for  hearing,  87 

Co-consciousness,  see  Personality, 
dual 


Coenesthesia,  see  Organic  senses 

Cognitive  experience  (or  Cognition, 
Knowledge)  =  an  experience  de- 
rived mainly  from  the  external 
senses,  120;  cf.  Perception,  Mem- 
ory, Imagination 

Cold  sense,  106  f 

Collateral  =  an  offshoot  of  the  nerve 
fiber  or  axon,  21 

Collection  (or  Summation)  =  the 
gathering  together  of  separate 
nerve  impulses  into  a  single  neuron 
or  path,  46 

Colligation  =  a  species  of  mental 
composition  in  which  the  elemen- 
tary sensations  maintain  their 
identity,  129 

Color  =  a  visual  sensation  in  which 
some  hue  predominates,  69  f 

—  complementary,  see  Complemen- 
taries 

—  fundamental  =  three  hues  so  cho- 
sen that  every  other  hue  can  be 
produced  by  combining  them,  74 

—  primal  =  four  specific  hues,  which 
are  believed  to  be  the  original 
colors  seen  by  man's  ancestors,  75 

—  pure  =  a  sensation  due  to  stimu- 
lation of  the  eye  by  light  of  uni- 
form wave-length,  69 

—  wave-lengths,  75 

—  2one  =  the  region  of  the  retina 
in  which  any  given  hue  is  dis- 
tinguishable, 80,  81 

Color  blindness  =  a  congenital  de- 
fect of  color  vision  in  which  cer- 
tain hues  appear  gray  or  are  in- 
distinguishable from  certain  other 
widely  distant  hues,  78  f 

Color  mixer  =  an  apparatus  for 
combining  two  or  more  different 
visual  stimuli  on  the  same  points 
of  the  retina,  69 

Color-shades  =  the  series  of  changes 
in  a  single  hue  produced  by  com- 
bining it  successively  with  each 
gray-shade,  72 

Color  spindle  (or  Color  pyramid)  = 
a  schematic  representation  of  all 
the  colors  and  grays  in  their  ob- 
served relations,  70  f 

Color-tone,  see  Hue 


GLOSSARY  AND  INDEX 


399 


Commissure  fibers  =  nerve  fibers 
which  connect  corresponding  cen- 
ters in  the  two  sides  of  the  brain  or 
cord,  33 

Communicatioii  =  any  act  of  social 
intercourse,  284 

Communicative  tendency  =  an  in- 
nate tendency  to  social  intercourse, 
243 

Complementaries  (or  Complements) 
=  two  hues  which  when  combined 
produce  gray,  76  f ;  black  and  white 
are  considered  complementaries, 
77 

Complex  =  (a)  a  composite  expe- 
rience; (b)  in  psychoanalysis:  a  sub- 
conscious (or  repressed)  emotional 
attitude,  pathological  in  nature, 
which  influences  one's  thoughts 
and    actions 

Composition  =  the  mental  process  of 
uniting  sensations  into  larger  ex- 
periences, 129 

Comprehension  =  (a)  understanding 
spoken  words,  291  n;  (b)  under- 
standing 

Conation  (or  Expressive  state)  =  an 
experience  made  up  largely  of 
motor  sensations,  224,  272 

Concept  =  a  special  type  of  thought 
which  tends  to  represent  truly  the 
characteristics  and  relations  of 
things,  297 

Concha  =  the  outer  shell  of  the  ear, 
85 

Conduct  =  behavior  which  is  di- 
rected toward  other  human  beings; 
social  behavior,  355 

Conduction  =  the  capacity  of  a  neu- 
ron to  propagate  a  nerve  impulse 
from  the  receiving  end  through  its 
entire  length  and  collateral  branch- 
es, 44 

—  line  =  the  path  traversed  by  any 
nerve  impulse  in  the  nervous  sys- 
tem, 22 

—  rate,  307 

Cones,  retinal  =  small  bodies  in  the 
retina  of  the  eye,  sensitive  to  both 
light  and  color,  60 

Conflict,  in  learning  =  two  or  more 
responses  involving  partly  similar 


neural  connections,  which  thereby 
interfere  with  the  fixation  of  a  hab- 
it, 257 
Conflicting  associations,  law,  188 
Conscience  =  an  attitude  arising  out 
of  social   relations  and   social  ex- 
periences, 341  f 
Conscious :  when  a  living  being  is  re- 
ceiving sensations  and  having  ex- 
periences, he  '  is  conscious,'  5,  123 

—  operation,  see  Mental  process 

—  phenomena,  see  Experience,  con- 
scious 

Consciousness  (or  Awareness)  =  a 
characteristic  of  mental  life;  the 
fact  that  a  being  has  experiences, 
122,  141;  c/.  Conscious 

—  field  of  =  an  individual's  total 
experiences  at  a  given  moment,  138 

—  lapsed  =  the  passage  of  con- 
sciousness into  subconsciousness 
which  takes  place  with  the  fixa- 
tion of  habits,  262 

—  marginal,  subliminal,  see  Expe- 
rience 

—  stream  of  =  the  general  succes- 
sion of  experiences,  306,  327 

Contiguity,  law,  185,  186 

Contrast  =  a  complementary  color 
effect  seen  on  a  white  surface  close 
beside  a  given  color  and  induced 
by  the  latter,  78 

Control  =  the  effect  of  nervous  and 
mental  adjustment  whereby  a  man 
or  other  creature  is  able  to  make 
responses  suitable  to  the  situation 
in  which  he  is  placed,  275,  315, 
372  ff 

—  center,  see  Center 
Convergence  =  fixating  the  foveas  of 

the  two  eyes  upon  a  single  point, 
156 

Convolution  (or  Gyre)  =  an  irregu- 
lar rounded  ridge  in  the  surface  of 
the  cerebrum,  Figs.  10-13 

Co&rdination  =  the  systematic  dis- 
tribution of  nerve  impulses  through 
various  motor  paths,  resulting  in 
an  orderly  response,  53  f 

Cord,  see  Spinal  cord 

Cornea  =  the  transparent  coat  on 
the  front  suriace  of  the  eye,  59 


400 


GLOSSARY  AND  INDEX 


Corpus  callosum,  see  Callosum 

Corpuscles  =  small  bodies  embed- 
ded in  the  skin,  which  serve  as  re- 
ceptors for  touch,  warmth,  and 
cold  stimuli,  106 

Corresponding  points,  retinal  =  any 
pair  of  points  in  the  two  retinas 
which  jdeld  a  single  sensation,  159 

Cortex  =  the  thin  layer  of  gray  mat- 
ter which  forms  the  outer  surface 
of  the  cerebrum,  31 

Corti,  organ  of  =  a  system  of  cells 
within  the  cochlear  duct  in  the 
cochlea  of  the  ear,  believed  to  be 
the  receptor  for  hearing,  87,  89 

Cranial  =  pertaining  to  the  head; 
cf.  Nerve 

Curiosity  =  (a)  an  innate  tendency 
to  seek  information,  242 ;  (b)  a  gen- 
eral term,  applied  to  many  specific 
motor  tendencies,  such  as  reaching, 
grasping,  biting,  \'isual  explora- 
tion, manipulation  of  objects,  etc. 

Cutaneous  senses,  107;  cf.  Touch, 
Warmth,  Cold 

Deliberation  =  the  delay,  accompa- 
nied by  thinking,  which  occurs  in 
voluntary  activity,  277 

Delusion  =  a  pathological  condi- 
tion in  which  imaginations  are  mis- 
taken for  reality,  200,  315 

JDemonstrations,  in  class  exercises, 
394 

Depth,  see  Perception 

Desire  =  an  attitude  embodying  the 
permanent  effects  of  feelings,  335  f 

Development,  mental  =  changes  and 
improvements  in  mental  opera- 
tions and  organization  which  oc- 
cur during  the  individual's  lifetime, 
360  f,  370  f;  cf.  Evolution 

Dextrality  =  an  innate  tendency  to 
prefer  one  hand,  etc.,  over  the  other 
in  performing  actions;  e.g.  right- 
handedness,  242 

Difference,  least  observable,  see 
Least  observable  difference 

Difference  tone  =  a  third  tone  which 
arises  when  two  tones  are  sounded 
together,  due  to  their  different  vi- 
bration rates,  95 


Diffused  expression  =  imperfectly 
coordinated  instinctive  behavior 
stimulated  by  general  systemic 
conditions,  239 

Diffused  response  (,or  movements), 
see  Response,  diffused 

Diffusion  =  an  indefinite  distribu- 
tion or  spreading  of  the  nerve  im- 
pulse, 256 

Digestive  sensations,  110 

Direction  =  (a)  the  angle  of  a  line 
or  contour  perceived  by  sight  or 
touch,  as  indicated  by  muscle  sen- 
sations or  otherwise,  152;  (b)  the 
position  of  a  visual  or  other  distant- 
sense  stimulus  with  reference  to 
the  observer,  as  indicated  by  mus- 
cle sensations  in  turning  the  eye 
or  otherwise 

Discrimination  =  the  mental  process 
of  separating  or  distinguishing  the 
parts  of  an  experience,  129 

—  perceptual,  see  Perception  of  dif- 
ference 

—  subconscious,  146 
Discrimination  time  =  the  duration 

of  that  portion  of  a  neural  process 
which  is  concerned  in  discrimina- 
tion, 310 

Disorganization,  mental  =  a  rever- 
sal of  the  process  of  systematic 
mental  organization,  369 

Disposition  =  an  attitude  which  em- 
bodies the  permanent  effects  of 
emotional  experiences,  337  f 

—  classification,  339 

Dissociation  (or  Dissociated  expe- 
rience), see  Experience,  subcon- 
scious 

Distance  apart  (or  Linear  distance) 
=  apparent  distance  of  objects 
from  one  another  in  the  plane  be- 
fore us,  150;  contrasted  with 
Depth,  or  distance  away  from  the 
observer 

Distribution  =  the  splitting  up  of  a 
single  nerve  impulse,  so  that  it 
passes  into  two  or  more  different 
paths  simultaneously,  47 

Dizziness  sensation,  119 

Dorsal  (or  Posterior)  =  toward  the 
back  of  the  body,  27 


GLOSSARY  AND  INDEX 


401 


Double  interpretation  illusion,  168  f 
Dream  =  a    special    type    of    expe- 
rience which  occurs  in  sleep,  317  ff 
Dual  personality,  see  Personality 
Duty,  sense    of  (or  Duty  attitude), 

342,  355 
Dynamic  sentiment  =  an  experience 
which  combines  a  feeling  with  an 
idea  of  power,  221 

Ear,  85  ff 

Education,  relation  to  mental  growth, 
372 

Effectors  (or  Motor  organs)  =  the 
organs  at  the  end  of  the  nervous 
arc  into  which  the  nerve  impulse 
is  finally  discharged;  muscles  and 
glands,  3,  5  n,  50 

—  relation  to  mental  organization, 
367 

Efferent  (or  Centrifugal)  =  motor, 
leading  from  the  center  toward  an 
effector 

Effort  experience,  272 

—  sensation,  116 
Electrolytic  stimulus,  in  taste,  43 
Element,  mental  =  a  simple  or  un- 

analyzed  component  of  expe- 
rience; e.g.  elementary  sensation 
(57,  126),  elementary  mental  op- 
eration (127  f,  130) 

Elimination,  law,  258 

Emotion  =  an  experience  made  up 
chiefly  of  systemic  and  motor  sen- 
sations, 209  ff 

—  classification,  214  f 

—  feeling  tone  of,  216 

—  relation  to  glands,  211 

—  training,  216  f 

Emotional  attitude,  see  Disposition 

—  bias  =  a  tendency  to  assume  an 
emotional  attitude  in  narrating, 
discussing,  or  thinking  about  ob- 
jective facts,  339 

End-brush  =  the  fine  branching  of 
fibrils  at  the  end  of  the  axon,  21 

Endolymph  =  a  liquid  which  fills 
the  semicircular  canals  and  sacs, 
117 

End-organs  (or  Terminal  organs)  = 
(a)  the  receptors  and  effectors  at 
the  terminals  of  the  nervous  arc. 


5,  9;  c/.  Receptors,  Effectors;  (b) 
commonly  limited  to  the  sense  or- 
gans or  receptors 
Environment  =  everything  that  acts 
from  outside  upon  an  organism,  2 

—  control,  see  Control. 
Equilibrium  sense,  see  Static  sense 
Esthetic   expression  =  an  innate  or 

acquired  tendency  to  esthetic  be- 
havior, i.e.  to  produce  some  work 
of  art  which  arouses  esthetic  sen- 
timent in  others,  243 

—  sentiment  =  an  experience  which 
combines  a  feeling  with  an  idea  of 
beauty  or  ugliness,  221 

Ethics,  relation  to  psychology,  296, 
344 

Euphoria  =  a  feeling  of  well-being, 
204 

Eustachian  tube  =  the  passage  ex- 
tending from  the  back  of  the  mouth 
to  the  middle  ear  behind  the  ear- 
drum, 86 

Evolution,  mental  =  changes  in  men- 
tal operations,  etc.,  which  take 
place  in  organic  species  from  gen- 
eration to  generation 

Excitation  =  the  capacity  of  neu- 
rons to  receive  nerve  impulses,  44 

Excitement  =  a  feeling  whose  tone 
is  neither  preeminently  pleasant 
nor  unpleasant,  207 

Exercises,  directions  in  using,  391 

Experience  (or  Mental  state.  State  of 
mind)  =  any  definite  impression, 
due  to  present  stimulation  or  to  re- 
vival of  former  impressions  or  to 
both;  any  moment  of  mental  life 
as  it  appears  to  the  individual 
himself;  an  organized  subjective 
occurrence;  e.g.  a  perception,  mem- 
ory, emotion,  2,  130 

—  conscious  =  an  experience  which 
forms  part  of  one's  personal  men- 
tal life,  5,  122,  126 

—  fundamental  (or  primary)  =  an 
experience  composed  largely  of  one 
single  class  of  sensations  (external, 
systemic,  or  motor),  or  of  ideas, 
130  f 

—  general  stream  of  =  the  succession 
of   various    sorts   of    experiences 


402 


GLOSSARY  AND  INDEX 


which  make  up  the  mental  life  of 
an  individual,  326  f 

—  marginal  =  a  faint  or  scarcely  ob- 
served conscious  experience,  128, 
137,  140,  326  f 

—  secondary  =  an  experience  com- 
posed of  two  or  more  classes  of 
sensations  or  ideas,  131 

—  subconscious  (or  subordinate, 
dissociated)  =  any  detached  ex- 
perience which  does  not  enter  into 
the  individual's  mental  life,  132, 
138 

—  subliminal  =  the  mental  effect 
produced  by  a  slight  stimulus  (or 
difference  of  stimuli)  which  is  too 
faint  to  be  consciously  observed, 
136,  344 

—  classification,  131,  304 

—  relation  to  response,  224 

Experiment  =  an  observation  of  na- 
ture in  which  certain  significant 
conditions  are  arranged  before- 
hand, 10  f 

Expression  =  (a)  the  sending  out  of 
a  motor  impulse,  275;  (b)  bodily 
changes  produced  by  motor  im- 
pulses; see  Response,  Facial,  etc. 

Expressive  experience,  see  Conation 

External  senses,  see  Sense 

Exteroceptor  =  an  external-sense  re- 
ceptor 

Eye,  58  f 

—  muscles,  63 

Facial  expression,  258 

Facilitation,  law  248 

Faintness,  law,  188 

Familiarity  feeling  =  a  quality  at- 
taching to  memories  and  to  certain 
perceptions,  which  indicates  that 
the  observer  has  had  a  similar  ex- 
perience before,  183,  195 

Fancy,  see  Imagination 

Far-sight  (or  Presbyopia)  =  a  fo- 
cusing defect  of  the  eye  due  to 
flattening  or  rigidity  of  the  lens, 
etc.,  whereby  one  can  see  distant 
objects  clearly,  while  near-by  ob- 
jects are  blurred,  64  n 

Fatigue  =  impairment  of  nerve, 
muscle,  or  receptor  due  to  over- 


work or  toxic  conditions,  46,  116, 
247 

Fear  emotion,  212 

Feeling  =  (a)  an  experience  in  which 
systemic  sensations  predominate; 
120,  203  ff;  (b)  often  used  to  de- 
note any  sensation,  203  n;  (c)  feel- 
ing tone;  (d)  popularly: '  to  feel' 
is  used  for  '  to  touch,'  '  to  believe,' 
etc.,  203  n 

—  curve  and  law,  207  f 

—  influence  on  thought,  206 

—  intensity,  207 

Feeling  tone  =  a  systemic  sensa- 
tion which  accompanies  other  sen- 
sations, probably  due  to  metabolic 
changes  in  the  bodily  tissues.  111, 
112,  204,  216 

Fiber,  see  Nerve  fiber 

Field,  see  Consciousness,  Visual 

Fissure  =  a  depth,  long  furrow  or 
cleft  in  the  cortical  surface  of  the 
brain,  31 

—  central  (or  Rolandic)  =  a  furrow 
on  the  right  and  left  sides  of  the 
brain,  which  starts  near  the  ear,  and 
runs  to  the  top  of  the  head,  31 

—  medial  =  a  deep  cleft  which  di- 
vides the  cerebrum  into  right  and 
left  hemispheres,  31 

—  Sylvian  =  a  horizontal  furrow  on 
the  right  an  d  left  sides  of  the  brain, 
about  the  level  of  the  ear,  31 

Fixation,  binocular,  see  Convergence 

—  of  habit  =  the  process  of  strength- 
ening an  acquired  connection  in 
the  nervous  system,  253,  256  ff 

—  visual  =  turning  the  eyeball  so 
that  a  given  object  lies  directly 
in  front  of  the  center  of  the  pupil 
and  fovea,  67 

Flavor  =  a  mingled  experience  of 
odor,  taste,  etc. 

Focus  of  attention  =  the  clearest 
portion  of  a  perception  or  idea,  161, 
327 

Focusing  the  eye  =  changing  the 
shape  of  the  lens  by  the  accommo- 
dation muscle,  so  as  to  make  a 
clear  picture  on  the  retina,  65 

—  binocular,  see  Convergence 
Forgetting^  187  f 


GLOSSARY  AND  INDEX 


403 


Form-board  =  a  board  with  depres- 
sions of  various  shapes  into  which 
solid  blocks  of  the  same  shapes 
are  to  be  inserted;  used  to  test 
perception  of  shape  or  form,  174  f 

Fovea  centralis  {or  Fovea)  =  a  de- 
pression in  the  retina  near  the  rear 
midpoint  of  the  eyeball,  where 
sight  is  clearest,  62 

Free  nerve-endings  =  sensory  neu- 
rons terminating  in  the  skin  and 
unattached  to  any  receptor;  they 
serve  for  the  reception  of  pain 
stimuli,  113 

Frequency,  law,  186 

Freudian  psychology,  see  Psycho- 
analysis 

Fringe  of  consciousness,  see  Expe- 
rience, marginal 

Function  {or  Operation,  Process)  = 
the  'working'  of  anything;  the 
way  in  which  something  is  accom- 
plished, 39  ff;  contrasted  with 
Structure 

—  biological  =  a  general  type  of 
bodily  process  which  serves  some 
biological  purpose,  237  f 

—  mental,  see  Mental  process 
Fusion  =  a  species  of  mental  com- 
position in  which  the  elementary 
sensations  merge  together,  129 

—  binocular  (binaural)  =  the  single 
set  of  impressions  which  results 
from  stimulation  of  the  two  eyes 
(ears),  159 

—  tonal  =  the  modified  effect  of 
two  or  more  tones  when  sounded 
together,  96 

Ganglion  =  a  small  collection  of 
nerve  cell-bodies;  see  Basal,  Spinal, 
Sympathetic 

Generative  {or  Sex)  sensations  = 
organic  sensations  whose  receptors 
are  in  the  generative  organs,  111 

Gesture  =  communication  by  move- 
ments of  the  hands,  etc.,  288 

Gland  =  a  cell,  tissue,  or  organ 
which  separates  materials  from 
the  blood  or  lymph  and  therewith 
produces  certain  chemical  com- 
pounds in  solution,   called  secre- 


tions, these  secretions  being  either 
discharged  directly  on  the  surface 
of  the  body,  or  through  ducts  to 
the  outside,  or  (in  case  of  endo- 
crine or  ductless  glands)  into  the 
blood  or  lymph,  51 

Glandular  response,  see  Response 

Graphic  language  =  communication 
by  means  of  durable  impressions  in 
some  material  substance,  289  f ;  cf. 
Language 

Gray  =  a  sensation  resulting  from 
mixed  light  stimuli  in  which  no 
single  wave-length  predominates, 
69,  71;  c/.  Shade 

Gray  matter  =  grayish-looking  mass- 
es of  nerve  tissue,  consisting  largely 
of  cell-bodies,  31 

Gustation,  see  Taste 

Gustatory  nerve  =  the  sensory  nerve 
for  taste 

Gyre  {or  Gyrus) ,  see  Convolution 

Hiibit  =  an  individually  acquired 
and  stereotyped  series  of  responses 
or  thoughts,  253 

—  mental  =  an  acquired  and  defi- 
nitely fixed  train  of  thoughts  or 
manner  of  thinking,  253 

—  motor  =  an  acquired  and  defi- 
nitely fixed  complex  motor  re- 
sponse, 254 

—  relation  to  intelligence,  262  f 

—  training,  267 

Habit    conation  =  a    sensory    expe- 
rience which  accompanies  the  per- 
formance of  an  habitual  act,  273 
Habit  formation,  see  Learning 
Hallucination  =  confusion  of  images 
or  thoughts  with  perceptions,  199 
Hearing  sense  {or  Audition),  85  ff 
Heat    sensation  =  a     mingled    im- 
pression of  warmth  and  cold,  107 
Hedonlc  =  pertaining  to  feeling 
Heft  =  to    receive  a  muscle   sensa- 
tion from  lifting,  162,  311 
Hemispheres,    cerebral,    see    Cere- 
brum 
Heredity  {or  Inheritance,  Heritage) 
=  (a)    any  effect  of  the  parental 
germ  cell  upon  the  nature  of  the 
new  creature,  366  f ;  (b)  the  char- 


404 


GLOSSARY  AND  INDEX 


acteristics  of  an  organism  so  far  as 
determined  by  characteristics  of 
the  germ  cell  from  which  it  start- 
ed; contrasted  with  Environment 

Hering  illusion,  170 

Hue  (or  Color-tone)  =  a  color  sensa- 
tion so  far  as  determined  by  the 
rate  of  light  vibration,  69  f 

Hunger  sensation,  110 

Hyperesthesia  =  a  condition  of 
heightened  sensitivity  of  certain 
receptors  or  sensory  paths,  138 

—  in  hypnosis,  322 

Hypesthesia  (or  Undersensitivity)  = 
a  condition  of  diminished  sensitiv- 
ity of  certain  receptors  or  sensory 
paths,  139 

Hypnosis  =  a  special  condition  of 
the  nervous  system  in  which  the 
individual  is  peculiarly  susceptible 
to  verbal  stimuli,  321  f 

Hypnotic  suggestion  =  an  effective 
verbal  stimulus  given  to  a  hyp- 
notized individual  by  another  per- 
son, 321 

Idea  (or  Ideation)  =  an  experience 
or  element  of  experience  due  to 
traces  left  in  the  brain  by  former 
nerve  impulses;  an  imagination  or 
thought,  131,  178;  contrasted  with 
Sensation  . 

Ideal  =  a  composite  experience 
which  includes  ideas,  feelings,  and 
motor  sensations,  281  f 

Ideational  =  pertaining  to  ideas  or 
to  ideation 

Ideograph  =  a  graphic  symbol  which 
denotes  a  word  or  idea;  e.g.  &,  2; 
contrasted  with  Letter,  which  de- 
notes a  sound  and  forms  part  of  a 
spoken  word,  289  n 

Ideomotor  activity  (or  behavior)  = 
a  response  generated  not  merely  by 
sensory  stimuli  but  by  their  idea- 
tional effects  in  the  brain,  274,  277 

Illusion  =  the  misinterpretation  of 
certain  factors  or  elements  in  an 
experience,  144,  199 

—  of  memory  =  the  misinterpreta- 
tion of  some  factor  in  a  memory 
experience,  198 


—  of  perception  =  a  perception 
which  in  some  respects  does  not 
correspond  to  the  actual  situation 
in  the  environment,  144  f,  154, 167  f 

Image  (or  Imagery)  =  a  group  of 
elementary  ideas  which  are  com- 
bined into  a  single  experience, 
178  ff 

—  anticipation  =  an  imagination 
which  has  a  lively  reference  to 
one's  future  actions  or  experiences, 
196 

—  composite  (or  free)  =  an  image 
resulting  from  the  revival  and  fu- 
sion of  several  past  experiences  due 
to  the  same  object  or  person,  196 

—  general  =  an  image  resulting 
from  the  revival  and  fusion  of  past 
experiences  of  many  similar  things, 
187 

—  imagination,  see  Imagination 

—  memory,  see  Memory 

—  retinal  (or  Retinal  picture)  =  the 
effects  of  retinal  stimulation  by 
any  single  object,  155 

—  systemic,  motor,  179 

—  classification,  178 

—  relation  to  perception,  179,  199  f 

—  training,  200 

Imagination  (or  Fancy)  =  (a)  an  im- 
age made  up  of  elements  from  two 
or  more  different  past  experiences, 
194  f;  (b)  popularly:  a  thought 
which  does  not  correspond  to 
reality 

—  relation  to  perception,  200 

—  training,  200 

Imitation  =  behavior  which  repro- 
duces the  responses  of  another 
creature  or  whose  results  resemble 
a  given  pattern  or  model,  241 

Impression  =  (a)  the  mental  process 
of  arousing  a  sensation  or  idea  or 
complex  experience,  127;  (b)  a 
sensation  or  idea,  121 

Impulse  =  (a)  a  special  sort  of  ac- 
tivity propagated  along  a  neuron 
(sensory,  central,  or  motor)  as  a 
result  of  stimulation,  3,  39,  44  f; 
(b)  popularly:  a  tendency  to  act, 
which  originates  in  the  brain  it- 
self 


GLOSSARY  AND  INDEX 


405 


Individuality  =  the  characteristics  in 
which  one  living  being  ('  individ- 
ual') differs  from  another,  361 

Inference  =  a  thought  which  is 
reached  by  reasoning,  323 

Inhibition  =  the  blocking  of  a  neu- 
ral pathway  so  that  the  progress  of 
the  nerve  impulse  is  checked,  255 

—  law,  189 

Innate  =  inherited ;  see  Heredity 
Instinct,  see  Behavior 

—  modified  =  a  mode  of  behavior  in 
which  the  inherited  nervous  ba- 
sis has  been  altered  by  the  forma- 
tion of  new  conduction  paths  dur- 
ing the  individual's   life-time,  237 

—  classification,  236,  238 

—  development,  243 

—  racial  origin,  236 

—  variability,  244 

Instinctive  conation  =  the  sensory 
experience  which  accompanies  an 
instinctive  response,  273 

—  tendency  =  a  tendency  to  act  so 
as  to  produce  a  certain  type  of  re- 
sult, the  tendency  being  due  to  in- 
nate conditions  while  the  behavior 
itself  may  be  acquired,  241  f 

Integration  =  the  systematic  as- 
sembling of  sensory  nerve  impulses 
in  the  brain  centers,  52  f 

Intellect  =  that  phase  of  character 
which  develops  as  a  result  of  an 
individual's  perceptions  and  ideas 
of  the  outer  world,  346  ff 

—  scale  =  any  graded  series  of  men- 
tal tests  designed  to  measure  an 
individual's  intellectual  develop- 
ment, 347  f ,  348  n 

Intelligence  =  (a)  the  degree  to 
which  intelligent  behavior  is  de- 
veloped in  an  individual  or  species; 
see  Behavior;  (b)  popularly:  a  syn- 
onym for  Intellect,  348  n 

—  animal,  251 

—  lapsed,  see  Consciousness,  lapsed 

—  development,  266 

—  relation  to  volition,  278 

Intelligence  quotient  (or  I.  Q.)  =  ra- 
tio of  an  individual's  '  mental  age' 
to  his  chronological  age;  used  as  a 
measure  of  mentality,  especially  on 


the   intellectual   side;   cf.   Mental 

age 
Intelligence   scale  =  (a)  a  measure 

of    mental    development;    (b)    a 

measure  or  scale  of   intellect,  347 
Intelligence    test  =  a    mental    test, 

348  n 
Intensity,  of  nerve  impulse,  43 

—  of  sensation,  80,  96,  101,  104,  108 
Interest  =  (a)    the    attitude    which 

embodies  the  permanent  effects  of 
perceptions  and  ideas,  335  f;  (b) 
the  feeling  tone  which  accompa- 
nies the  interest  attitude 

Interoceptor  =  a  systemic-sense  re- 
ceptor 

Interval,  musical  =  any  pitch  in- 
terval used  in  music,  92,  93 

—  pitch  =  the  relation  of  two  tones, 
as  measured  by  the  relation  of  their 
vibration-rates,  94 

Introspection,  see  Self-observation 
Iris  =  a  flat,  ring-shaped  muscle  in 
front  of  the  lens,  which  regulates 
the  amount  of  light  admitted  to  the 
eye;  the  colored  ring  which  sur- 
rounds the  pupil,  60,  63 
Itching  sensation,  107 

James-Lange  theory  of  emotion,  210 

Jastrow    cylinders  =  an    apparatus 

for     investigating    pressure     and 

muscle  sensations,  136  f,  146 

Judgment  =  a  thought  in  which  two 

concepts  are  combined,  297 

Katabolism,  see  Catabolism 
Kinesthetic  sense  (or    Kinesthesia, 

Kinesthesis),  see  Muscle  sense 
Knee-jerk  reflex,  37,  248 
conditioned,  248 

Labyrinth  =  the  inner  ear,  86 
Ladd-Franklin  theory  of  sight,  83 
Language  =  an      experience      com- 
posed of    ideas  and  motor  sensa- 
tions, whose  motor  expression  re- 
sults in  communication,  285,  287  3 

—  center,  see  Center 

—  development,  299  f 

—  types,  287 

Learning    (or    Habit    formation)  => 


406 


GLOSSARY  AND  INDEX 


the  process  of  forming  new  con- 
nections in  the  nervous  arc  and 
perfecting  them  through  repeti- 
tion, 253  ff 

—  by  associative  memory  =  a  meth- 
od of  learning  characterized  by  a 
flow  of  ideas  ending  with  the  idea 
of  the  appropriate  response,  265 

—  by  trial  and  error  =  a  method  of 
learning  characterized  by  persis- 
tent, varied  responses  ending  acci- 
dentally with  a  successful  or  ap- 
propriate response,  263  f 

—  in  long  and  short  periods,  261 

—  measurement  of,  259,  260 
Least  observable   difference,  147  f; 

c/.  Threshold  of  discrimination 

sensation,  81,  96,  101,  105,  108, 

116,  119;  c/.  Threshold  of  sensa- 
tion 

Lens  of  eye,  59 

Lies,  children's,  195,  296 

Light  waves  =  very  minute  trans- 
verse vibrations  in  the  ether, 
which  give  rise  to  sensations  of 
sight,  67 

Lobe  =  a  large  division  of  the  cor- 
tex; each  hemisphere  includes  a 
frontal,  parietal,  temporal,  and 
occipital  lobe,  with  an  inner  con- 
cealed cortical  region,  the  island 
of  Reil,  31 

Local  sign  =  a  slight  modification 
of  sensation  which  serves  to  indi-' 
cate  what  particular  point  in  the 
retina  or  skin  is  stimulated;  local 
signs  are  due  not  to  the  stimulus 
but  to  the  receptor,  and  are  simi- 
lar for  all  sensations  from  a  given 
receptor,  150 

Location  of  memories,  181 

Loudness  =  intensity  of  sound,  96 

Love  emotion,  213 

Macula  lutea  (or  Yellow  spot)  =  the 
central  region  of  the  retina,  which 
has  a  yellowish  tinge,  62 

Marginal  (or  Margin  of)  conscious- 
ness, see  Experience,  marginal 

Maze  (or  Labyrinth)  =  a  construc- 
tion consisting  of  an  intricate  set  of 
branching  (walled)  paths,  includ- 


ing blind  alleys,  with  only  one 
route  leading  to  the  goal;  used  to 
measure  the  learning  ability  of 
animals  or  human  beings,  251  f 
Meaning  =  a  group  of  marginal 
elements  in  a  cognitive  experience, 
which  have  reference  to  the  corre- 
sponding external  situation,  295  f ; 
cf.  Value 

—  attitude,  341 

—  in  perception  =  ideas  of  the  use 
of  an  object,  or  of  any  other  inti- 
mate relation,  which  accompany 
perception,  173 

—  in  reasoning,  323 

—  in  thought  =  the  faint  images  of 
objects  which  accompany  verbal 
thinking,  295  f 

Meatus,  external  =  the  passageway 
into  the  ear,  which  conveys  sound 
waves  to  the  drum,  85 

Medulla  oblongata  (or  Bulb)  =  the 
lowest  part  of  the  brain,  just  above 
the  spinal  cord,  29,  30 

Memory  =  (a)  a  synonym  for  re- 
vival, 127;  cf.  Revival;  (b)  a  mem- 
ory image;  the  renewal  of  a  former 
experience,  180  fif 

—  training,  191 

Memory  system  =  an  artificial  de- 
vice to  assist  recollection,  193 

Mental  =  (a)  pertaining  to  mind  or 
any  of  its  factors;  (b)  more  broadly, 
used  to  characterize  the  organized 
activities  of  the  nervous  system  or 
the  resulting  conscious  experiences 

—  age  =  degree  of  mental  develop- 
ment expressed  in  terms  of  the  age 
at  which  the  average  of  mankind 
attain  that  degree,  348 

—  condition  (underlying  or  perma- 
nent) =  any  arrangement  of  nerve 
structure  or  connections,  either 
inherited  or  acquired,  which  molds 
or  modifies  one's  experiences  and 
responses,  331 

—  development,  see  Development 

—  life  =  the  stream  of  experiences 
and  nervous  activity  in  any  or- 
ganism, 35,  55,  327 

—  organization,  see  Organization 

—  process  (or  operation)  =  (a)  any 


GLOSSARY  AND  INDEX 


407 


change  in  the  elementary  sensa- 
tions when  they  reach  the  higher 
centers,  resulting  in  the  formation 
of  definite  experiences,  127  f,  130; 
(b)  often  used  to  denote  the  suc- 
cession of  experiences 
— -  scale  =  a  graded  series  of  mental 
tests,  347 

—  state,  see  Experience 

—  succession,  see  Succession 

—  test  =  a  practical  device  for  meas- 
uring an  individual's  mental  de- 
velopment by  his  success  in  an- 
swering questions,  solving  prob- 
lems, or  performing  prescribed 
acts,  15,  347  f 

Mentality  =  the  degree  of  an  in- 
dividual's mental  development,  361 

Metabolism  =  chemical  changes  in 
the  body,  110  n,  112;  cf.  Anabol- 
ism,  Catabolism 

Mind  =  the  total  organization  of  ex- 
periences and  personality  in  an 
individual,  17,  124  n,  365,  380 

Mirror-writing  (or  Mirror-script), 
163,  290 

Mnemonic  =  pertaining  to  memory 

Modification  =  the  capacity  of  a 
nerve  impulse  to  change  its  form, 
48  f 

Monocular,  see  Uniocular 

Mood,  see  Disposition 

Moral  attitude,  see  Conscience 

—  character,  see  Morality 

—  sentiment  =  an  experience  which 
combines  a  feeling  with  the  idea  of 
right-and-wrong,  222 

Morality  =  that  phase  of  character 
which  concerns  man's  relations  to 
his  fellows  and  is  developed  by 
social  experiences,  354  f 

Moron  =  a  slightly  retarded  human 
being,  16  n 

Motive  =  a  conscious  or  subcon- 
scious condition  which  plays  a  part 
in  determining  one's  behavior  or 
conduct,  283,  337,  349,  355 

Motor  experience  {or  Motor  con- 
sciousness) =  organized  informa- 
tion concerning  one's  own  move- 
ments, 120,  224,  271 ;  c/.  Conation 

—  organs,  see  Effectors 


—  senses,  see  Sense 

Movement  =  motion  of  an  organ- 
ism or  its  parts,  produced  by  nerve 
impulses  acting  upon  the  muscles; 
cf.  Behavior,  Response 

Miiller-Lyer  illusion,  170 

Muscle  =  a  contractile  tissue  op- 
erated by  the  motor  nerves,  50  f 

—  antagonistic,  see  Antagonists 
Muscle   (or  ELinesthetic)   sense  =  a 

sense  whose  receptors  lie  in  the 
muscles  and  other  organs  of  move- 
ment, 115  f,  151 
Myopia,  see  Near-sight 

Nausea  sensation.  111,  112,  119 
Near-sight  {or  Myopia)  =  a  focusing 
defect  of  the  eye,  due  to  too  much 
curvature  of  the  lens,  whereby  dis- 
tant objects  are  blurred,  64  n 
Nerve  =  a  bundle  of  neurons  lying 
side  by  side,  and  serving  to  con- 
duct nerve  impulses,  3,  26 

—  cranial  =  a  nerve  connecting  with 
some  receptor  or  effector  in  the 
head,  26,  29 

—  motor  =  a  nerve  leading  from  the 
cord  or  brain  to  some  efifector,  26 

—  peripheral  =  a  nerve  connecting 
the  spinal  cord  or  brain  with  a  re- 
ceptor or  effector,  26 

—  sensory  =  a  nerve  leading  from 
some  receptor  to  the  cord  or  brain, 
26 

—  spinal  =  a  nerve  which  passes 
from  the  body  (below  the  head) 
into  the  spinal  cord,  26,  29 

Nerve  fiber  =  the  main  stem  of  a 
neuron,  21 

Nerve  impulse,  see  Impulse 

Nerve-study  =  in  psychology:  the 
study  of  the  nervous  system  and 
its  activities  as  bearing  on  mental 
life,  9 

Nervous  arc  {or  circuit)  =  the  com- 
plete path  traversed  by  any  nerve 
impulse  from  receptor  to  effector, 
23,39 

levels,  302  f 

Nervous  system  =  the  sum-total  of 
neurons  (nerve  cells)  in  the  body, 
3,  6,  19  £f,  39  S 


408 


GLOSSARY  AND  INDEX 


• autonomic  {or  sympathetic)  = 

a  semi-dependent  system  of  nerves 
and  ganglia  distributed  through 
the  body,  which  controls  the  bod- 
ily functions,  34  f,  351 

central  =  the  brain  and  cord 

cerebrospinal  =  the  main  part 

of  the  nervous  system,  excluding 
the  autonomic  nerves,  26  n 

peripheral  =  the    spinal     and 

cranial  nerves 

operation,  39  ff 

relation  to  mental  organiza- 
tion, 367 

structure,  19  ff 

Neural  =  pertaining  to  the  nervous 
system  or  to  neurons 

Neuron  {or  Neurone)  =  a  single 
nerve  cell,  including  the  cell-body, 
axon,  and  all  branches,  21  f 

—  secondary  =  a  neuron  which  does 
not  connect  directly  with  a  recep- 
tor or  effector,  but  only  through 
another  neuron,  28 

—  properties,  44  f 

Noise  =  an  auditory  sensation  due 
to  a  general  mixture  of  different 
sound  waves,  90,  96 

Nucleus  =  (a)  a  small  spherical  mass 
of  organized  protoplasm  within 
each  cell,  essential  to  its  life,  19; 
(b)  in  neurology:  a  small  group  of 
nerve  cells  in  the  cord  or  brain 

Object  =  in  psychology:  a  physical 
mass  which  stimulates  a  bunch  of 
receptors,  yielding  a  more  or  less 
complicated  but  unified  percep- 
tion, 162 

—  perception,  see  Perception 
Objective  =  pertaining  to  the  exter- 
nal world 

Observation  =  attentive    study    of 

events  as  they  occur,  7 
Odor  =  a  sensation  of  smell,  99 

—  prism,  101 
Olfaction,  see  Smell 
Olfactometer  =  an     apparatus     for 

testing  the  sense  of  smell,  101 
Olfactory  nerve  =  the  sensory  nerve 

for  smell,  99 
Operation,  see  Functioa 


Optic  nerve  =  the  sensory  nerve  for 
sight,  65  f 

—  chiasm,  see  Chiasm 

—  thalamus,  see  Thalami 

Organ  =  an  associated  mass  of  cells 
in  the  body  which  performs  some 
definite  process  or  function 

Organic  sense  =  the  sense  or  senses 
whose  receptors  lie  in  the  diges- 
tive, reproductive,  respiratory,  and 
other  bodily  organs,  110  f 

Organism  =  a  living  plant  or  ani- 
mal, including  man,  365  n 

Organization  =  any  group  or  system 
of  interworking  parts,  365 

—  mental  =  the  entire  central  ner- 
vous structure,  which  (in  connec- 
tion with  stimuli)  determines  the 
individual's  experiences  and  re- 
sponses, 365  ff 

Otoliths  =  small  solid  particles 
within  the  utricle  and  saccule,  118 

Overtone  {or  Harmonic)  =  a  JFaint 
tone  accompanying  the  tone  which 
is  sounded,  due  to  subsidiary  vi- 
brations of  the  instrument  in  some 
multiple  rate  of  the  main  or  funda- 
mental tone,  94 

Pain  sense,  113  f 

—  stimuli,  42 

Palp  =  to  receive  a  touch  sensation, 
162,  164,  204  n,  311 

Path  {or  Pathway)  =  the  line  along 
which  a  nerve  impulse  proceeds 
through  the  chain  of  neurons  in  a 
nervous  arc,  39,  55,  226  f ,  235, 247  f, 
253  ff 

Pawlow's  experiment,  for  measuring 
the  strength  of  a  conditioned  re- 
sponse by  the  flow  of  saliva,  249 

Perception  =  an  experience  (usu- 
ally complex)  due  chiefly  to  direct 
impressions  from  the  external 
senses,  143  ff 

—  binocular,  see  Binocular  Vision 

—  errors  of,  see  Illusion 

—  of  depth  {or  Projection)  =  per- 
ception of  the  distance  of  objects 
from  the  observer's  body,  153  ff; 
contrasted  with  Perception  of  sur- 
face 


GLOSSARY  AND  INDEX 


409 


—  of  difference,  146 

—  of  direction,  152 

—  of  objects,  161  f,  165 

—  of  rhythm  =  the  grouping  of  a 
succession  of  tones,  etc.,  into  a 
pattern,  emphasizing  one  tone  in 
each  group  of  three,  four,  etc.,  166 

—  of  space  =  perception  of  depth 
or  of  surface,  149,  164 

—  of  surface  =  perception  of  the 
shape,  direction,  and  apartness  of 
objects  in  a  Sat  field  before  us, 
taking  no  account  of  their  distance 
away  from  the  observer's  body, 
149  ff ;  contrasted  with  Perception 
of  depth 

—  of  time  and  events,  165 

—  stream  of  =  a  succession  of  per- 
ceptions uninterrupted  by  other 
experiences,  311  f 

—  affected  by  habit,  163 

—  agreement  with  the  external  sit- 
uation, 143,  167 

—  by  the  blind.  161 

—  classification,  146 

—  relation  to  brain,  171 

—  training,  173 
Perception  time,  310 

Perimeter  =  an  apparatus  for  in- 
vestigating sensations  received 
from  the  periphery  of  the  retina,  74 

Periphery  of  retina  =  the  region  far- 
thest from  the  fovea,  63,  80,  83 

Personal  equation,  law,  315 

Personal  identity  =  (a)  the  continu- 
ity of  one's  entire  mental  life,  362; 
(b)  the  feeling  that  all  one's  past 
experiences  belong  to  the  same  in- 
dividual, 362 

Personality  {or  Self)  =  the  total  out- 
come of  an  individual's  mental  or- 
ganization, comprising  all  his  per- 
manent mental  conditions  and  or- 
ganized experiences  at  any  period 
of  life,  134.  332,  360  ff 

—  dual,  multiple  (,or  Co-conscious- 
ness) =  a  mental  disorder  in 
which  two  or  more  distinct  per- 
sonalities occur  in  the  same  indi- 
vidual, now  one,  now  another  be- 
ing dominant,  363;  qf.  Personal- 
ity, secondaxy 


—  secondary  =  an  organized  group 
of  split-off  experiences,  capable  of 
becoming  dominant;  362;  cf.  Per- 
sonality, dual 

—  problems,  364 

—  rating,  360 

Perspective,  spatial  =  perception  of 
the  relative  distance  of  objects 
(or  their  parts)  from  the  observer, 
155,  161 

—  temporal  =  memory  of  the  rela- 
tive distance  in  time  of  various 
past  experiences  from  the  present 
moment,  183 

Pitch  =  quality  of  tone  as  deter- 
mined by  the  rate  of  sound-wave 
vibration,  91 

—  absolute  =  ability  to  recognize 
or  identify  any  given  tone,  91 

—  relative  =  ability  to  recognize  or 
reproduce  pitch  intervals,  aa  in 
humming  a  tune,  92 

—  standards,  91 

Plateau  =  a  temporary  halt  in  the 
progress  of  learning,  261 

Play  =  an  innate  tendency  to  per- 
form acts  not  directly  concerned 
with  bodily  or  mental  welfare,  as 
an  outlet  for  nervous  energy,  242 

Pleasantness  =  a  feeling  tone  prob- 
ably due  to  anabolism,  111 

Poggendorff  illusion,  171  f 

Pons  Varolii  =  a  broad  band  of  neu- 
rons which  extends  laterally  across 
the  medulla,  29 

Present,  perceptual  =  a  short  period 
of  time  during  which  a  succession 
of  experiences  seem  to  be  before  UB 
all  together.  165 

Pressure  sensation,  107 

Problem  attitude  {or  Aufgabe)  » 
the  attitude  which  enables  one  to 
keep  a  given  question  or  problem 
in  the  foreground,  265.  340 

Process,  see  Function 

Proclivity  =  an  attitude  embodsdng 
the  permanent  effects  of  volitions, 
341.  344 

Projection,  perceptual  =  the  per- 
ception of  objects  as  situated  at  a 
distance  from  the  observer's  body; 
see  Perception  of  depth 


410 


GLOSSARY  AND  INDEX 


—  in  touch,  160 

—  of  sounds,  odors,  temperatures, 
159  f 

—  visual,  158  f 

Projection  center  (or  area),  see  Cen- 
ter, cortical 

Proof-reader's  illusion,  168 

Property  =  a  characteristic  of  any- 
thing, either  as  regards  its  make- 
up (structure)  or  in  its  capacity  to 
act  in  certain  ways  (function), 
44  f;  cf.  Structure,  Function 

Proposition  =  the  language  equiva- 
lent of  a  judgment,  298 

Proprioceptor  =  a  motor-sense  re- 
ceptor 

Protoplasm  =  a  name  given  to  the 
chemical  substances  which  com- 
ix>se  an  organism 

Psychiatry  =  the  study  of  mental 
disorders  ('  psychoses ') 

Psychoanalysis  =  a  method  em- 
ployed by  Freud  and  others  to 
bring  subconscious  impressions 
into  the  foreground,  134 

Psychology  =  the  systematic  study 
of  events  arising  out  of  the  inter- 
action between  an  organism  and 
its  environment  by  means  of  re- 
ceptors, nervous  system,  and  ef- 
fectors, 1,  5 

—  abnormal  =  the  study  of  disor- 
dered or  undeveloiJed  minds,  13 

—  animal  =  the  study  of  the  mental 
life  of  animals,  exclusive  of  man,  13 

—  applied  =  the  practical  applica- 
tion of  psj'chological  principles  to 
the  affairs  of  life,  15,  380  f,  394 

—  child  =  the  study  of  mental  de- 
velopment in  the  human  young,  13 

—  comparative  =  the  comparative 
study  of  mental  life  in  various  ani- 
mal species,  13 

—  experimental  =  the  experimental 
study  of  human  mental  life  in  the 
laboratory,  14 

■ —  general  =  psychology  of  the  nor- 
mal adult  human  being,  12 

—  human  =  the  science  which  deals 
with  the  interaction  between  man 
and  his  environment  by  means  of 
the  nervous  system  and  its  termi- 


nal organs,  together  with  the  ac- 
companying mental  events,  5,  12 

—  physiological  (or  neurological)  = 
the  study  of  the  nervous  system  in 
its  relations  to  mental  life,  14 

—  social  =  the  study  of  mental  life 
as  influenced  by  the  interaction 
of  individuals  upon  one  another,  16 

—  branches,  12  f 

—  methods  of  research,  8  f 

—  practical  bearings,  380  f,  394 

—  problems,  5,  365 
Psychophysics  =  the      experimental 

study  of  the  relation  between 
stimuli  and  sensations,  15 

Punishment,  educative  effects,  356  f 

Pupil  =  a  circular  opening  in  the  iris 
through  which  light  is  admitted  to 
the  eye,  60 

Purkinje  phenomenon  =  a  variation 
in  the  relative  brightness  of  differ- 
ent hues  in  brilliant  and  dim  il- 
lumination, 76 

Purple  hues  =  a  series  of  colors  not 
found  in  the  spectrum,  produced  by 
combining  red  and  violet  light- 
waves, 70,  73 

Purpose,  biological  =  the  prolonga- 
tion^of  life  or  perpetuation  of  the 
species  so  far  as  this  depends  upon 
the  creature's  bodily  processes,  237 

Purpose  idea  =  an  anticipation  im- 
age or  thought  of  what  one  is  go- 
ing to  accomplish  by  his  own  motor 
initiative,  275,  280 

Quality  =  any  characteristic  of  stim- 
uli, sensations,  and  experiences 
which  is  not  quantitative  nor  di- 
rectly expressible  in  numbers; 
sort;  kind 

—  of  sensation,  68  f,  90,  99,  104, 
107,  110,  113,  116,  119 

—  of  stimulus,  43 

Rational  behavior,  control,  thought; 
see  Behavior,  Control,  Thought 

Rationalization  =  the  mental  proc- 
ess of  constructing  artificial  rea- 
sons to  justify  an  inference  which 
is  actually  based  on  other  grounds, 
326 


GLOSSARY  AND  INDEX 


411 


Reaction,  see  Response 

Reaction  time  =  the  time  interval 
between  stimulation  and  response, 
307  f 

Reading  =  seeing  and  understand- 
ing written  words  or  any  graphic 
expression,  291 

Reading  aloud  =  the  translation  of 
graphic  symbols  into  speech,  292 

Reality  feeling  =  the  sentiment  or 
conviction  that  the  perceived  ex- 
ternal objects  are  real,  220 

Reason  =  the  ability  to  think  or  act 
rationally,  298;  cf.  Thought,  Be- 
havior 

Reasoning  =  a  succession  of  rational 
thoughts  in  which  all  the  connec- 
tions correspond  to  actual  relations 
or  processes  of  nature,  322  ff 

—  error  =  an  unobserved  substitu- 
tion of  a  casual  association  for  a 
rational  inference  in  a  train  of  rea- 
soning, 324 

Recency,  law,  187 

Receptor  {or  Sense  organ)  =  a  spe- 
cial organ  at  the  beginning  of  the 
nervous  arc,  which  receives  stimuli 
and  excites  a  sensory  neuron,  lead- 
ing to  sensation,  3,  67,  68  f,  85, 
99,  103,  107,  117 

—  in  muscles,  51 

—  relation  to  mental  growth,  366 
Recognition  =  the   identification   of 

the  present  memory  or  perception 
with  a  previous  experience,  184 

Recollection  =  the  arousing  of  a 
memory  image,  184  f 

Reflex  =  a  definite  response  to  a 
definite  stimulus,  due  to  an  inher- 
ited arrangement  of  nerve  paths, 
40,  226,  229  ff 

—  antagonistic  =  a  pair  of  reflexes 
which  involve  antagonistic  muscles, 
232 

—  compound  =  a  reflex  which  in- 
volves two  or  more  related  muscles, 
231 

—  conditioned  =  a  reflex  in  which 
the  inherited  nervous  connections 
have  been  altered  by  use,  248  ff 

—  cranial  =  a  reflex  whose  center 
lies  within  the  head,  40,  231 


—  higher  =  a  reflex  which  involves 
some  higher  center,  so  that  the  re- 
sponse is  delayed,  230 

—  spinal  =  a  reflex  which  involves 
nothing  above  the  spinal  cord,  37, 
40 

—  classification,  233  f 

Reflex  conation  =  an  experience 
which  accompanies  a  reflex,  273 

Relief  =  perception  of  the  relative 
distance  of  different  parts  of  an 
object  or  scene  from  the  observer, 
155;  c/.  Perspective 

Religious  character  and  conduct,  16, 
355 

Resistance  experience,  272 

Respiratory  sensations.  111 

Response  {or  Reaction)  =  any  activ- 
ity of  muscles  or  glands  due  to 
motor  nerve  impulses,  with  the  re- 
sulting bodily  movements  and 
changes;  the  end-result  of  stimu- 
lation, 9,  49  f ;  cf.  Behavior 

—  adaptive,  see  Adaptation 

—  automatic  =  any  response  which 
takes  place  without  delay  or  de- 
liberation, 279 

—  diffused  =  an  uncodrdinated  re- 
sponse, in  which  the  motor  impulse 
spreads  to  several  muscles  and  the 
action  bears  no  significant  relation 
to  the  stimulating  situation,  225  f, 
239 

—  glandular  =  a  response  which 
involves  activity  of  the  glands 
(secretion),  51 

—  implicit  —  adjustment  of  the  vocal 
muscles  without  actual  utterance, 
295  n 

—  muscular  =  a  response  which  in- 
volves muscular  contraction,  50 

—  social  =  a  response  which  di- 
rectly concerns  other  beings  of  the 
species  and  tends  to  bring  about  a 
social  relation,  354 

—  classification,  214,  225 
Retardation,  mental  =  stunted  men- 
tal growth,  14 

Retention  =  the  capacity  of  neurons 
to  preserve  traces  of  the  impres- 
sions produced  by  excitation,  45 

—  in  memory,  180 


412 


GLOSSARY  AND  INDEX 


Retina  =  a  thin  coat  which   covers 
the  inner  surface  of  the    eyeball 
except  in   front  and   contains  mi- 
nute  rods  and  cones  sensitive  to 
light,  60 
Reversible  perspective  illusion,  168 
Review  questions,  directions,  392 
Revival  =  the   mental   operation   of 
renewing  or  repeating  a  former  ex- 
perience, 127,  180 
Reward,  educative  effects,  356  f 
Right-handedness,  see  Deztrality 
Rods,    retinal  =  minute    bodies    in 
the  retina  of  the  eye,    sensitive  to 
light  but  not  to  color,  60 
Rolando,  fissure  of,  see  Fissure 

Saccule  =  a  spherical  hollow  or  sac 
near  the  semicircular  canals,  part 
of  the  static-sense  receptor,  118 

Sacs,  see  Utricle,  Saccule 

Salivary  reflex,  249 

Satisfaction  =  a  type  of  desire  atti- 
tude which  embodies  the  perma- 
nent effects  of  pleasant  experiences 
(appetites),  336 

Saturation  (or  Chroma)  =  the  rela- 
tive amount  of  pure  hue  to  gray  in 
a  given  color  sensation,  72,  73;  cf. 
Tints 

Scala  tympani,  Scala  vestibuli  =  two 
tubes  running  side  by  side  within 
the  cochlea,  87 

Scale,  auditory  =  the  series  of  audi- 
ble tones  from  deepest  to  shrillest, 
91 

—  mental,  see  Mental  scale 

—  musical  =  a  group  of  tones  com- 
prising certain  definite  pitch  inter- 
vals, used  in  musical  composition, 
93 

Sclerotic  (or  Sclera)  =  the  outer 
coating  of  the  eyeball,  covering  all 
but  the  front  surface;  the  '  white  of 
the  eye,'  69 

Self,  see  Personality 

Self-consciousness  =  (a)  conscious- 
ness or  experience  of  our  own  per- 
sonality, 364;  (b)  popular  use:  em- 
barrassment, 364  n 

Self-control  =  (a)  ability  to  modify 
or  direct  one's  own  behavior,  377; 


(b)  inhibition  of  one's  emotional 
expression 

Self-notion  (or  Notion  of  self)  =  the 
total  experience  of  one's  own  per- 
sonality, 363 

Self-observation  (or  Introspection) 
=  the  systematic  study  and  re- 
porting of  one's  own  individual  ex- 
periences, 8,  125 

Self-perception,  364 

Self-preservation  instinct  =  a  gener- 
al term  used  to  denote  the  useful- 
ness of  instinctive  behavior  to  pre- 
serve the  creature's  life,  243 

Self-study,  see  Self-observation 

Semicircular  canals,  see  Canals 

Sensation  =  an  impression  due  to 
stimulation  of  the  receptors,  57, 
68,  90,  99,  103,  143  n;  cf.  Sense 

—  secondary  motor  =  any  sensation 
of  sight,  touch,  etc.  which  assists 
one  in  the  perception  of  his  own 
movements,  116,  272 

Sense  =  a  mechanism  for  receiving 
information  through  stimulation, 
57  ff;  cf.  Sight,  Hearing,  etc. 

—  to  =  to  receive  impressions 
through  the  senses,  203  n 

—  contiguous  =  a  sense  which  is 
stimulated  by  objects  in  immediate 
contact  with  the  body,  57,  102 

—  distant  =  a  sense  whose  stimuli 
originate  in  objects  at  a  distance 
from  the  body,  57,  102 

—  external  =  any  sense  which  is 
stimulated  by  objects  outside  the 
body,  57,  119 

— motor  =  any  sense  which  is  stim- 
ulated by  movement  or  position  of 
the  body  or  its  members,  57,  114, 
120 

—  systemic  =  any  sense  which  is 
stimulated  by  conditions  and 
changes  within  the  body,  57,  109, 
120 

—  classification,  58,  119  f 

Sense  organ,  see  Receptor 

Sensibility,  general  =  a  general  feel- 
ing tone  pervading  the  whole  body, 
112 

Sensitivity  (or  Irritability)  =  capa- 
city of  the  receptors  to   receive 


GLOSSARY  AND  INDEX 


413 


stimulation  or  of  the  sensory  nerves 
to  transmit  nerve  impulses,  139  f ; 
c/.  Excitation 

Sensorimotor  activity  =  a  response 
due  chiefly  to  sensory  stimuli  and 
not  to  ideational  effects  in  the 
brain,  274 

Sentiment  =  an  experience  made  up 
chiefly  of  ideas  and  systemic  sensa- 
tions, 218  ff 

—  classification,  220 
Set,  neural,  see  Trace 

Sex  sensations,  see  Generative  sen- 
sations 

Shade  =  the  relative  brightness  or 
.darkness  of  a  gray  sensation  or  of  a 
color  sensation,  71 

Shades  (or  Gray-shades)  =  the  se- 
ries of  grays  from  white  to  black, 
71;  c/.  Color-shades 

Sight  sense  (or  Vision),  58  ff 

Similarity  and  contiguity,  law,  185, 
186 

Situation  =  the  entire  aggregate  of 
stimuli  at  a  given  moment,  171, 
263.  360,  380 

Skill  =  that  phase  of  character 
which  develops  out  of  the  individ- 
ual's motor  attitudes  and  habits, 
352  f 

—  scale  =  any  graded  series  of  tests 
designed  to  measure  the  develop- 
ment of  skill  in  an  individual,  353 

Sleep  =  a   special   condition  of  the 
nervous  system,  in  which  the  syn- 
apses are  highly  resistant  to  the 
passage  of  nerve  impulses,  317;  cf. 
Dreams 
Smell  sense  (or  Olfaction),  98  f 
Social  factors,  371;  cf.  Control 
Somesthetic  sense,  see  Touch 
Somnambulism  =  sleep-walking,  not 
controlled    by    the    higher    brain 
centers,  318 
Sound   waves  =  longitudinal   vibra- 
tions of  the  air  or  of  solid  bodies  or 
their  particles,  which  give  rise  to 
sensations  of  hearing,  88 
Space  perception,  see  Perception 
Span,  see  Attention 
Spectral  lines  =  certain  bright  lines 
observed  in  sun-light,  etc.  when 


the  different  waves  are  separated 
by  passing  through  a  prism,  75 

Spectrum  =  the  entire  series  of  vis- 
ible light  waves,  68 

Speech  (or  Vocal  language)  =  com- 
munication by  production  of 
sounds  with  the  mouth,  etc.,  288; 
cf.  Language 

Speed,  see  Facilitation 

Spinal  =  pertaining  to  the  spinal 
cord 

—  cord  (or  Cord)  =  a  mass  of  neurons 
within  the  back-bone,  forming 
paths  of  conduction,  26  f 

—  ganglion  =  an  enlargement  of  the 
sensory  nerve  just  outside  the 
cord,  containing  cell-bodies  of 
sensory  neurons,  27 

—  nerve,  see  Nerve 

Split-off  experience  =  an  experience 
which  is  not  connected  with  the 
main  stream  of  the  individual's  ex- 
periences, 362;  cf.  Subconscious; 
Personality,  secondary 

Staircase  illusion,  169 

State,  mental,  see  Experience 

Static  sense  =  a  sense  whose  recep- 
tors lie  in  the  semicircular  canals 
and  sacs  of  the  inner  ear,  and 
which  furnishes  information  of  one's 
position  and  changes  of  position  in 
space,  117  f 

Stereoscope  =  an  apparatus  by 
means  of  which  two  slightly  dis- 
similar pictures,  seen  by  the  two 
eyes,  are  perceived  as  one  and 
stand  out  in  relief,  157  f 

Stereoscopic  vision,  see  Binocular 
vision 

Stilling  test  =  an  apparatus  for  in- 
vestigating color  blindness,  80 

Stimulation  =  (a)  an  effect  produced 
in  a  receptor  and  the  adjacent  neu- 
ron by  some  object  or  force  out- 
side the  nervous  system,  41  f ;  (b) 
often  used  for  Excitation 

Stimulus  =  anything  which  causes 
stimulation  and  starts  a  nerve  im- 
pulse, 9,  39,  42,  99,  103,  107;  cf. 
Sight,   Hearing,  etc. 

— relation  to  mental  organization,  370 

Strain  sensation,  116 


414 


GLOSSARY  AND  INDEX 


Stratton's  experiment,  of  the  re- 
versed visual  field,  165 

Stream  of  consciousness,  thought, 
etc.;  see  Consciousness,  Thought, 
etc. 

Structure  =  the  shape  or  composi- 
tion or  arrangement  of  parts  of 
anything,  19  ff;  contrasted  with 
Function 

Subconscious :  when  an  impression  is 
received  but  does  not  enter  into 
the  individual's  conscious  experi- 
ence, the  effect  is  called  '  subcon- 
scious,' 123;  cf.  Experience,  Atti- 
tude, Dreams 

Subconsciousness  =  the  fact  of  hav- 
ing subconscious  impressions  or 
experiences,  133 

Subjective  =  (a)  experienced  or 
sensed  by  an  individual;  (b)  con- 
scious or  subconscious 

Sublimation  =  a  term  used  by  some 
psychologists  to  denote  the  purifi- 
cation or  elevation  of  motives  from 
primitive  instinctive  tendencies 

Sublime  =  a  sentiment  which  com- 
bines a  feeling  with  the  idea  of  both 
beauty  and  power,  221 

Subliminal,  see  Experience 

Succession,  mental  =  the  sequence 
of  experiences  or  responses,  306  ff ; 
cf.  Association 

Suggestion  =  (a)  the  mental  process 
by  which  one  idea  passes  over  into 
another,  127;  (b)  popular  use: 
words  or  actions  of  another  person 
which  serve  to  guide  one's  thinking 
or  behavior,  281 

Suggestions,  in  using  this  book,  391  ff 

Summaries,  16,  36,  65,  121,  141,  176, 
201,  222,  245,  269,  282,  304,  329, 
358 

Superstition  =  belief  in  a  concept  or 
judgment  which  has  been  shown 
not  to  correspond  to  nature,  325 

Sylvius,  fissure  of  =  see  Fissure 

Symbolic  experience  =  an  experi- 
ence which  does  not  resemble  or 
correspond  to  the  situation  which 
it  represents,  286 

Sympathetic  system,  see  Nervous 
system,  autonomic 


—  ganglia  =  distributing  centers  in 
the  autonomic  system,  34 

Sympathy  emotion,  213 

Synapse  =  the  place  of  connection 
between  two  neurons,  where  their 
end-fibrils  intermesh,  23  f,  254  f 

Synesthesia  =  persistent  association 
of  a  certain  color  with  a  certain 
sound,  or  any  other  arbitrary 
grouping  of  sensations 

Systemic  senses,  see  Sense 

Tachistoscope  =  an  instrument  for 
exposing  a  word,  picture,  etc.,  to 
view  for  a  fraction  of  a  second ;  used 
in  investigating  visual  perception 

Taste  sense  (or  Gustation),  103  f 

Telepathy  =  a  direct  means  of  com- 
munication supposed  by  some  psy- 
chologists to  exist  between  human 
beings,  in  which  the  receptors  are 
not  concerned,  284 

Temperament  =  that  phase  of  char- 
acter which  develops  out  of  the  in- 
dividual's desires  and  emotional 
attitudes,  350  f 

—  classification,  351 
Temperature   senses,   see   Warmth, 

Cold 

Tendency  =  the  effect  of  inherited 
or  acquired  conditions  in  the  nerv- 
ous system,  favoring  certain  par- 
ticular modes  of  behavior;  cf.  In- 
stinctive tendency 

Term  =  the  language  equivalent  of  a 
concept,  298 

Terminal  organs,  see  End-organs 

Test,  see  Mental  test 

Thalami,  optic  =  an  important  pair 
of  nerve  tracts  (basal  ganglia)  be- 
neath the  cortex,  which  contain 
the  primary  sensory  centers,  30 

Thinking  =  a  train  or  succession  of 
thoughts,  312  ff 

—  abstract,  324 

—  rational,  see  Reasoning 
Thirst  sensation.  111 

Thought  =  a  type  of  experience  akin 
to  language,  composed  of  symbolic 
ideas  and  motor  sensations,  which 
tends  to  supplant  pure  imagery  in 
the  human  species,  285,  294  ff 


GLOSSARY  AND  INDEX 


415 


—  Control  =  the  directing  of  a  suc- 
cession of  thoughts  along  a  given 
line,  313  f 

—  attitude,  see  Appreciation 

—  center,  see  Center 

—  rational  =  a  thought  in  wlych  the 
meaning  or  value  is  prominent, 
297  f 

—  stream  of  =  a  succession  of 
thoughts  and  images  uninterrupted 
by  other  experiences,  312;  cf. 
Thinking 

—  classification,  294 

—  development,  300 

—  rapidity,  307 

—  training,  300 

"threshold  (or  Limen)  of  sensation  = 
the  point  at  which,  with  increasing 
intensity  of  stimulation,  a  sensa- 
tion just  begins  to  be  observed, 
136  f;  cf.  Least  observable  sensa- 
tion 

—  of  discrimination  =  the  point  at 
which,  with  increasing  difference 
of  intensity  between  two  stimuli, 
their  difference  just  begins  to  be 
observed ;  cf.  Least  observable  dif- 
ference 

Tickle  sensation,  108 

Timbre,  95 

Time  perception,  see  Perception 

—  perspective,  see  Perspective 
Tingling  sensation,  107 

Tints  =  the  series  of  changes  in  any 
given  hue  produced  by  combining 
it  in  various  proportions  with  a 
gray,  72 

Tone,  auditory  =  a  sensation  due  to 
stimulation  of  the  ear  by  sound 
vibrations  of  uniform  wave-length, 
90 

Tongues  =  the  various  human  lan- 
guages, 288 

Tonus  (or  Tone)  of  muscles  =  a 
condition  of  tension  or  stretch  in 
the  muscles  which  exists  apart 
from  specific  stimulation 

Touch  (or  Tactile)  sense,  106 

Trace  (or  Set)  =  a  more  or  less  per- 
manent mark  of  former  nerve  im- 
pulses preser\'ed  in  the  nerve  sub- 
stance, 45,  331;  cf.  Retention 


Tract  =  a  bundle  of  nerve  fibers  in 
the  spinal  cord  or  brain,  66 

Trait  =  a  rather  generalized  atti- 
tude; the  sum-total  of  traits  in  any 
one  phase  of  experience  make  up 
the  corresponding  phase  of  charac- 
ter, 346 

Transformation  (or  Mental  chemis- 
try) =  the  mental  operation  by 
which  the  nature  or  quality  of  an 
experience  becomes  altered,  130  n 

Trial  and  error,  see  Learning 

Tropism  =  a  response  resembling  a 
reflex  which  occurs  in  lower  organ- 
isms, especially  those  which  have 
no  nervous  system 

Tympanum  =  the  ear-drum,  85 

Types,  mental  =  differences  among 
individuals  in  the  prominence  of 
one  sense  or  one  phase  of  character 
over  others;  e.g.  auditory,  motor 
type;  intellectual,  temperamental 
type,  373  ff 

Unconsciousness  =  a  condition  of 
the  living  organism  in  which  (to 
all  appearances)  no  impressions 
are  taking  place;  e.g.  dreamless 
sleep ;  often  used  for  Subconscious- 
ness 

Undersensitivity,  see  Hypesthesia 

Understanding  =  the  arousal  in  one 
individual  of  an  experience  cor- 
responding to  some  experience  of 
another  individual  through  the  lat- 
ter's  speech  or  writing,  291 

Uniocular  (or  Monocular)  perception 
=  visual  perception  in  which  only 
one  eye  is  concerned,  153  f 

Unpleasantness  =  a  feeling  tone  prob- 
ably due  to  catabolism,  111,  114 

—  relation  to  pain,  114 

Utricle  =  a  spherical  hollow  or  sac 
near  the  semicircular  canals,  part 
of  the  static-sense  receptor,  118 

Valae  (or  Idea  of  value)  =  the  idea  of 
the  actual  intensity  or  quantita- 
tive properties  of  objects,  events, 
situations,  etc.,  which  accompanies 
verbal  thinking,  219,  295;  ef. 
Meaning 


416 


GLOSSARY  AND  INDEX 


—  attitude,  341 
Vascular  sensations,  111 

Ventral  (or  Anterior)  =  toward  the 
front  of  the  body,  27 

Vestibule  =  the  midportion  of  the 
inner  ear,  87 

Visceral  sense,  see  Organic  senses 

Vision,  see  Sight 

Visual  field  =  the  entire  range  of  vis- 
ual sensations  at  any  moment,  158 

—  theory  =  an  attempt  to  explain 
how  the  eye  furnishes  color  sensa- 
tions and  to  account  for  visual  phe- 
nomena generally,  82  f 

Vividness  (or  Attention,  Mental  fo- 
cusing) =  (a)  the  mental  operation 
by  which  sensations  or  experiences 
become  distinct  or  noticeable  irre- 
spective of  the  intensity  of  stimu- 
lation, 128;  (b)  the  prominence  of 
some  part  of  an  experience,  wheth- 
er due  to  intensity  of  stimulation 
or  to  a  central  process,  162 

—  in  perception,  162 

—  law,  186 

Vocal  language,  see  Speech 

Volition  =  a      complex      experience 

made  up  chiefly  of  motor  sensations 

and  ideas,  120,  276  fl 


—  its  automatic  expression,  279 

—  training,  279 

Voluntary  activity,  see  Ideomotor 
activity 

Walking  =  a  modified  instinct,  244 

Want  =  a  type  of  desire  attitude 
which  embodies  the  permanent 
effects  of  unpleasant  experiences 
(aversions),  336 

Warmth  sense,  106 

Weber's  law  =  a  statement  of  the 
quantitative  relations  between 
stimuli  and  sensations,  148,  149 

Whirl  experience,  272 

Will,  275  n,  see  Volition 

Windows,  oval  (Fenestra  ovalis)  and 
round  (F.  rotunda)  =  two  win- 
dows in  the  wall  between  the  mid- 
dle ear  and  inner  ear,  86 

Wink  reflex,  40 

Word,  a  unit  of  thought  or  language, 
285 

World,  external  (or  outer);  see  En- 
vironment 

Writing,  see  Graphic  language 

ZSllner  illusion,  171 


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